The GTX 660 is a nice card, but if you can get the Ti version, I'd defenitely recommend that. On the other hand the GTX 760 should perform even better and has more bandwith. It will be more futureproof and you can always go for a SLi setup if you feel like games doesn't run like you require. So, I'd recommend you to go for the 660 Ti, but if you can affort a little more, the GTX 760 will be a better choose in lomg terms.
To answer your latest question: 2 GB of Vram is defenitely needed if you want to play the latest games in 1080p. If you want to play on even higherdesolutions, I'd recommend you to even get a 3 GB model. 1 GB is too low unless you are planning to play on lower resolutions like 720p.