As a retired tech support guy I must speak up here. The likelihood of a remote connection being the cause of data corruption is virtually nil. More likely is this: Data corruption will often be present on a drive but unknown to the user until the corrupted data blocks are used (read from or written to). Any data written to the corrupted blocks will also be corrupted, and the corruption can even spread on the drive as new files are added. Moving large numbers of files is likely to cause such corruption to manifest. Time for data rescue measures, and please don't blame Adobe.

Yes, you can use the external. In Lightroom just create a new catalog and place it on the external drive. Once that is done you can import the photos on the drive into that catalog.

Naw, I'm just a perfectionist nerd 🤓.

It's true that at modern camera resolutions, and when saving with low compression (high quality), it takes many generations of re-saves for compression artifacts to become obvious.

I'm extra cautious because in my job (I.T. for an art school) I see someone get bitten by over-use of JPG compression several times per semester.

Good to know. Thanks for the clarification. 👍

Yep. JPG is a "lossy" compression format. That means it compresses the file by taking an average of neighboring pixels and lumping them together, so you lose some detail every time you save. A fun test is to take a photo and save it as JPG with a fairly high compression setting. Re-save it several times and you will start to see the artifacts of JPG compression.
JPG can be great for emailing images but don't use it while you're editing and saving.

Oh, and @rwilson1942 is spot on: Unless you need to use Photoshop you don't need to bother with saving PSD files.
I only use Photoshop for complex editing jobs. Otherwise I go straight from LR to either TIF or PNG.

PSD is Photoshop's native format. It allows you to save files with adjustment features not part of the TIF specification. TIF is a standard format useful for exchange between different software and hardware. I generally use Photoshop for it's layering capabilities, so I save PSD files in case I want to go back to tweak the file. Once the PSD file is ready for production, flatten the layers and export a TIF version, then drop it into Illustrator, InDesign, or whatever you use when a project will be headed to a printing company. If the image is headed to the web I'd export a PNG file. My two cents...

Nice captures, Danniel. Priceless opera singer exertions on #4. Belt it out baby!

1. You can upgrade the RAM on 27" iMacs. I wouldn't pay Apple's outrageous RAM prices.
2. I'd get an i7 CPU. In addition to better performance in general, it is a factor in extending the useful life of the computer.
3. Does LR take advantage of Radeon GPUs? If so, then the Radeon 580 would likely be worth the extra $$.
4. If you're going to spend extra on internal storage don't bother with the 3TB FD. Go all the way to the 500GB SSD.

My pick for the iMac: i7 CPU, Radeon 580 (if supported by LR), 8GB RAM, 500GB SSD.
3rd party add-ons: 32 GB RAM, and maybe an external SSD for your LR library.

I never locate my LR libraries on the internal drive, so that why I selected a 500GB for the internal.

Enjoy your new iMac!

That looks like a pleco. They are often hard-skinned and spiny. Might have been just as well the heron couldn't swallow it. Nice shot!

You may have some corruption in the directory structure (as opposed to the drive hardware or the data). For this I highly recommend Disk Warrior. Find it on Alsoft.com. It is a tool that repairs and rebuilds the disk directory. Think of it as the card catalog that tells the computer where files are located on the disk. It can get corrupted, and Disk Utility will never know, but Disk Warrior can probably fix it. At $120 it isn't cheap, but after 20 years supporting Mac users in a large university setting I can say that it is the most useful tool I have in my troubleshooting software collection.

On back-ups:

First, I don't usually back up the entire drive, which is why I also don't use Time Machine. I recommend users back up their home directory only, which should contain all their irreplaceable data. This economizes disk space, and the OS and applications can (and should) be completely reinstalled after a drive failure anyway, so backing them up is pretty pointless.

Second, I tend not to buy backup drives larger than 1 TB (unless the user is working with a lot of video) as having too much data on one device constitutes a glaring single point of failure. I prefer to use a redundant backup system consisting of optical disks (used to be DVD, now it's BluRay) as deep backup for the original photos, and bare 1TB drives with separate power supplies and SATA-to-USB adapters as working disks which are retired annually. This way the points of failure are isolated, I can replace parts cheaply and easily, and redundancy is maximized. I recommend buying at least one 1TB drive a year and a good disk catalog software (NeoFinder!) so you can keep track of what is on the drives you collect over the years. Each drive gets it's own Lightroom library with which you work throughout the year. At the end of the year back up the disk catalog and any other miscellaneous files you choose onto that year's drive, label it, and put it on a shelf. During that process you'll copy any current projects onto the new year's drive.
I hope that helps...

Try using corn starch on it. It's a bit messy, so you'll want to seal off the sensitive parts and be careful how you apply it. You need to use enough to react with the goo and turn it into not-goo. In my experience this will greatly slow the disintegration process, and it will let you touch the rubber parts without getting goo on your hands.

For the past 20 years I've been one guy supporting over 200 Macs in a large university art department, and I agree with most of the points posted by bpulv. That said, I will take issue with one point and add another.

Bundled software: I would down-check this one. In the real world students will eventually be required to use or trade files with users of Microsoft Office. While Pages and Numbers are good apps and can indeed read and write Word and Excel files, the workflows and feature sets of the two pairs are pretty different, and formatting is very tough (nearly impossible, actually) to keep straight when you work cross-platform on a regular basis (style sheets, anyone?). The bottom line is that Office is almost always a necessity for Mac users. While the classroom experience may not require Office, we owe it to our students to teach them software they are likely to encounter in the business world. I don't particularly like MS Word, but for the forseeable future it is the center of the word processing universe.

As an aside I will say that Keynote is, IMO, far superior to Powerpoint. Yet this too is a trap if you swap presentation files with PP users, since several very cool features of Keynote don't work on PP. Always test your Keynote file in PP before handing it off to a PP user!

An additional point in favor of Macs that was inferred but not explicit: Apple builds both the OS and the hardware, so the driver and compatibility hassles found in the Windows world are almost non-existent for Mac users. Even a Mac-based Windows setup is less hassle because Bootcamp installs a full set of Windows drivers when you set it up. Cost of ownership goes way down when you don't have to spend time or money solving hardware incompatibilities and driver issues.

Interesting problem to have. To my knowledge, updates to Camera Raw always replace the old one, so that original version shouldn't even be around. The idea that it is raises all sorts of questions, but I'll start with "what editing app are you using?"

And I always express the weight of my camera in mg. Hm, so that'd be about 2,000,000 mg with lens...