All of the dx vs fx stuff is good discussion. I would say though that if you are just starting out, or worried about prices, the D610 is an extremely capable FX camera. Camera bodies will depreciate in value much more then lenses, and think about how much you are going to lose on each camera if you decide to sell it. When I've bought my cameras, I have usually gone in with the mindset that I will get maybe 25%-50% of the price you paid back if you decide to sell it down the road.
Lenses hold value more then bodies. I prefer zooms much more then primes to be honest. I used to have a lot of gear, but have pretty much downsized to a few lenses and one camera body. It is fun to have a wide variety of lenses, they are cool, but I feel like you will most likely just use a couple consistently. I shoot many many different types of styles of photography, and I feel like it isn't necessary to get too wrapped up into which lens to buy or which camera to buy until you start shooting, and shooting more often. I would go cheap with the bodies and lenses until you figure out what type of photos are the bulk of your photography and go from there, with slow upgrades over time.