If your colors are looking off the first thing I would do is look at what you are viewing them on. Is your monitor of the IPS variety? and have you calibrated it / checked the calibration recently? If not and you "Correct" your images either by changing camera settings or post processing you might find out later on when you get prints made or switch monitors that all your effort has to be redone.

That being said personally I tend to set most of my cameras for Vivid colors because it just looks better to me as a preference.

I have an Epson V550 that does a good job, but I didn't like the software and ended up picking up VueScan 64. to make it a less painless process. There was another software option to go with an existing scanner but their licensing agreement was too unfriendly / limited. In the end I think it all depends on how much time you want to spend and what your intended use is. If you have bulk slides most of your standard scanners are slow enough to require the patience of a saint to do quantity, but many of the cheaper film / slide specific scanners are faster but with much lower quality results.

One thing I did do that tested out pretty good was to take a LED light board and set it up with guides for slides and then use my D7100 with macro extension tubes on a tripod with remote, which actually worked out pretty good since I could then shoot in RAW and use my normal post processing and work flow and I could capture a lot of images quickly. (which is the way that I will go in the future unless I have just a few slides or slides that are in rough shape where I want to use digital ICE, etc. to recover the images). Below is the setup I used.

It doesn't matter what you do for a living... If you're not happy doing it change the situation if you can afford it... or change the Job at the first practical opportunity. Sorry to hear your talents won't be available, but if your relieved it's a good thing.

I currently have a D7100 and just recently purchased a V5 for an always with me camera for light carry with the 10-30 PD, 30-110 Nikon One lenses then added the FT1 lens adapter and a 55-300 and 55-200 DX Zooms which I chose primarily to keep size and Weight down. So far I am very happy with this setup keeping in mind the limitations of the smaller sensor on the V5. The up side is the compact 300 gives 810mm equivalent zoom in a package you can walk around with. For Comparison my V5 with FT1 and 55-300 is virtually the same size as my D7100 with my 18-140 and comes in at 2 lbs 2 oz vs. the D7100 2 lbs 14 oz.

If you want to see some examples check out the "Killdeer Nesting" "Lion in your Living Room" and "St. Andrews Heron's" folders in my gallery here:

http://etherialoneinnc.deviantart.com/gallery/

I've not had this setup long so I'm still playing around with it but I'm pretty happy with it for a walk about, just remember to keep several batteries charged as the J5's battery life is short, and if you do go with an FT1 and DX lenses a hand grip to screw into the FT1 makes shooting a lot easier especially when using the long end of the zoom.

Hmmm ... I just searched for Camera Rules for the Indy 500 and couldn't find anything stating a no camera policy, the only thing I could find was a "No Professional Camera" exclusion that stated Concerts only. Where did you find the Info?

This is what I found:
https://www.indianapolismotorspeedway.com/events/indy500/fan-info/gate-search-policy

I know from my limited experience at events in the past I've seen the "No Professional Camera" policy or in some cases "No Interchangeable Lens Camera" policy, but So far I've never been turned away or questioned bringing and using my mirrorless cameras, However I've never tried bringing my Nikon 1 with a full sized DX lens and adapter either. I think the real truth is that as long as it doesn't look like a full sized DSLR most of the time the folks doing security don't really care, especially with everyone taking video with their phone etc.

I've purchased factory refurbished computers before and never had any issues with them aside from one where I couldn't register for the warranty which wasn't really an issue as I never had a problem with it. But then I think more often than not Computers, like Cameras are usually returned either out of buyers remorse or the buyer not fully understanding the products capabilities and limitations rather than because it had some other problem. As for getting refurbished components? I might be a little more hesitant there, and I would never purchase a refurbished hard drive or SSD as hardware is cheap to replace compared to your critical data that sometimes especially in the case of photography irreplaceable and lets be honest.. most of us don't back up our data as often as we should.

If I remember right it pulled up my Tamron lenses, but I didn't check for any sigma

This might also help... If you go to this link then pick a couple of lenses that you are thinking about (like a Prime and a Zoom that covers the prime) and open each in a new tab.

Then on each tab if they did the full review there is a section on the Right that shows a graphic titled "Blur". If you click on it an interactive window will pop up and allow you to select different f stops and Zoom values for a Zoom lens and it will show you that lenses clarity at the given settings across the frame, the pop ups are also small enough that you can compare two or three lenses at t time this way.

This is the link for their Nikon DX Lens Reviews: http://www.imaging-resource.com/lenses/tag/dx/

I think all choices you listed are good. To me the IQ and even limited light performance with both Nikon's APS-C's and FX Cameras is fantastic. I'm still using APS-C (D7100) and I'm very happy with it, and though I've thought about going FX I like shooting wildlife and like the extra magnification of APS-C and with 24MP (7100/7200 ... the 7500 drops to 21MP) I've not found it lacking in any way, so if your more likely to shoot long distance, or have a compliment of DX series lenses I would stick with the 7xxx series. Or if Low Light performance is Critical / Slightly better IQ go with the 610 / 750.

I don't know how you feel about Refurbished gear and or used, but I just picked up a Nikon 1 J5 (20mp with Tilting LCD) refurb for $400 with the 10-30 PD Zoom (27-81mm equivalent) then added a used Very Good Condition 30-110 (81-297mm equivalent) for $144... add in a couple of decent 32gb memory cards (the J5 uses MicroSD) and a couple of extra spare batteries and your right around $700 for the whole deal.

If you want a longer zoom you can add an FT1 Adapter ($150 Used if you keep an eye out) to be able to use AF-S full sized DX / FX lenses rather than pay close to $1k for the Nikon 1 70-300 zoom, which is the way I went. I added in a used Nikon 55-200 AF-S VR (148-540mm equivalent) and a 55-300 AF-S VR (148-810mm equivalent) for $85 and $166 repsectively. So far I have been very happy with the results and amazed at how light the J5 and 200mm zoom are just for walking around compared to lugging my D7100 with a 70-300 or 80-400. Granted the 55-200/300 don't have quite the clarity of the latter but between ease of carry and the smaller sensor using the best part of glass only I can't complain.

Here's a link to some of the results (edited and resized with Capture One): http://etherialoneinnc.deviantart.com/gallery/

I've gone up to 1/500th of a second and still had good motion blur on the propeller.. but found that especially in shot's where you have a ground or background reference slower shutters give a better motion effect unless you want to show more detail in the background such as with aircraft passing one another where you want to have clarity on subjects with different speeds, etc.

I've used some of the cheaper cards of different brands as well as some good ones and I've never had any fail. That being said I'm using Sandisk Extreme Pro and Sandisk Extreme in my D7100 not so much because I think my data is safer but it really sucks if your shooting heavy and fill your buffer then have to wait for it to clear and in those moments a good high speed card are worth every penny!

On the same subject I just recently had to buy several new cards as I just picked up a Nikon 1 J5 to replace my older J1 and it takes Micro SD Cards. Since I had to buy them anyway I picked up a few different types to see if there was much of a difference, especially since the J5 can shoot 20 frames a second (or actually up to 60) filling the buffer is very easy to do. So at any rate I did a little informal testing with the different cards filling the buffer then timing the cards. I also tested using the reset times on the Slow motion video clips since on the J5 they are limited to three seconds so often you will try to take several clips if possible.

Anyway here is a short version of what I came up with with the attached PDF being the Original Document (I didn't realize I could just attach it until AFTER I typed all of this up - Duh!)

When I did the burst I was shooting in RAW + Fine Jpeg with the buffer being good for 20 frames and the Camera having to process and write about 700mb of files per burst.

I then measured from the time time the shutter button was pressed until I had half of the buffer available (10 frames), the full buffer available (20 frames) and then finally when the memory card Access Light went out / processing stopped for each card.

I repeated this three times then averaged the results. Also I noticed that other things impacted the times like focusing the camera to check the buffer level (the first time for each card took longer because I was checking more often for when the various points would be reached, so if I was to shoot burst mode I would definitely use AF-S only and limit focusing if my buffer wasn't clear.

Anyway here are the numbers for what I had in my little test

Time To---------------------------> | 10F Avail_ | Buffer Clear_ | Write Complete
---------------------------------------------------------------------------------------------
Lexar 32gb 1000x U3, HC II, C10 | 15 Sec____ | 1 Min 3 Sec_ | 1 Min 33 Sec
---------------------------------------------------------------------------------------------
Samsung Pro 21gb, U3 HC I ____ | 15 Sec____ | 1 Min 6 Sec_ | 1 Min 40 Sec
---------------------------------------------------------------------------------------------
SanDisk Ultra 32gb, U1, HC I ___ | 11 Sec____ | 1 Min 0 Sec_ | 1 Min 41 Sec
---------------------------------------------------------------------------------------------
PNY 32gb Class 4 (Basic Card) __ | 14 Sec____ | 1 Min 41 Sec | 2 Min 50 Sec
---------------------------------------------------------------------------------------------

Surprisingly when I did the Slow Motion Video Clips at different resolutions all of the better cards performed about the same, with resets of under 5 seconds / 2 seconds after the previous clip stopped recording) for 120 & 400 fps clips with the 1200fps clips running from 10.5-12 seconds due to processing, with the PNY card lagging by 1.5 seconds @ 400 FPS and 1.5-3 seconds at 1200fps.

So looking at all of this my take on it is a faster card is good, but unless you try different brands / speeds with your particular camera it's still a crap shoot any you may not get any better performance out of a $50 card than you do a $25 one based more on luck of the draw than anything.

Attached file:
(Download)

Ditto on the extension tubes... they are a nice addition to the camera bag and allow you to play around with a lot of different set ups for not a lot of $$$ and then if you find you need or want more step into macro lenses.

I picked up a set of Vello extension tubes for Nikon (12mm, 20mm & 36mm) on Amazon a few months ago for $79. And they are decent and work as advertised, but If i had to do it over I would have spent the extra $50 and purchased the Kenko set instead. The reason for this is because the inside of the Kenko Tubes are lined with Camera Black or at least a black anti-reflective coating where the Vello tubes use a very fine adhesive backed velour fabric to line the barrels which with age etc. could be a issue if it starts to deteriorate.

I shoot RAW just because I like my Steaks almost to the same level.

One thing to Remember that may or may not apply to your situation... The D90 has an internal focus motor, so if your using any lenses that don't have built in focus motors make sure your replacement camera is one of the higher end ones that still have the focus drive built in. The D7xxx series mentioned above all have the motors, and I have been very pleased with my D7100.

As you stated to keep all your glass you will want to stay with a DX / APS-C sized sensor since the DX lenses image circle will not fully illuminate a FX sensor, and if you stick with a body with the focus motor built in you will also have the option of getting and using some relatively inexpensive older Nikon glass that is wonderful, with the only real down side being that they don't focus as fast as the newer lenses and may not have VR or have the earlier versions of VR, and also as has already been mentioned KEH.com is a good place to get used Cameras and Glass (I've used them multiple times and have been very satisfied).