If you're relatively new to dslr photography, I'd start with a more basic body like a 3200 or possibly 5400 and learn everything you can about that camera. You'll probably increase your lens collection.
By the time you have your chosen camera mastered, Nikon will have produced an upgrade from the D850. At that point you may wish to purchase the latest or simply wait another few years for a later
body with more whistles and bells. I've used a D300 for several years which I'm still learning.
50 1.8, 17-55, 70-300 and several others not used
One of the best sources that addresses this question is Bryan Peterson's Understanding Exposure. Many consider this the bible for exposure in photography.
The author walks you thru all the variables and provides an in-depth explanation of the exposure triangle. If you don't have this book, I'd encourage you to
purchase it, or at least borrow it from another photographer. Amazon usually has this in stock. Good luck!
I've been shooting Nikon for about 12 years. Three lenses that have been used most often:
(1) 50mm 1.8
(2) 85-300
(3) 17-55
Don't know if the last is made anymore. You can usually find one on a for sale board. It's pretty pricey, but takes awesome pictures.
IMHO the 50mm should be in every photographer's lens collection. It's relatively cheap and one of the better primes. Good luck with your D850.
I upgraded from a D50 to a D300 several years ago. All my lenses work on both cameras. I suspect you can include the D100-D300 series in the lens compatibility family.
My wife and I have visited Alaska twice. The last one was several years ago where we took a cross country tour sponsored by Holland America. You have some
stunning pictures which bring back many fond memories. Thanks for sharing!
It's certainly not the cheapest, but in terms of bang-for-the-buck I've had very good luck with Photoshop Elements. It comes with Adobe Camera Raw, which means you can shoot your D750 in raw
mode. If you've saved the raw version of any of your old pics, they can also be edited using PSE. Amazon is currently selling PSE 15 for $60.
Well done! Like your bird shots.