You should be fine with a 970, it's not going to be "the fastest", but it more than meets the requirements, there are piles of guys flying DCS with 970s and Rifts. There is also a tool in Steam you can run, which will analyse your system and run it through a few VR like tests, and tell you your score and where you sit. I tested on older PC I had months ago, it was a 3820 with a 980SLI set up (it just uses one card for the tests, as VR + SLi = no go right now). It tested very high, I forget exactly how high, but it surprised me where it was, so based on that and what I've seen with other players in other games and their system specs, you should be OK.
http://store.steampowered.com/app/323910/Glasses fit in both the Rift and Vive, it just depends on your frame size regarding how well they fit. I have some regular sized glasses I wear for distance, but don't need up close, but they way the VR units focus, if you need glasses at all, odds are you'll want them on. I wear contacts mostly when using VR, but I have used my glasses, and they work ok, just be careful of the lenses of the VR that you don't bash your glasses into them when putting them on, they'll take some contact but it is possible to scratch them if you really hit them hard I've heard. No issues with that on my end so far. You may want to find an anti-fog spray for your glasses, as they can fog a bit after time depending on how hot you get/etc.
