I dt look at the above posts so i answer directly to your question.
1. 2GB is enough for 1080P gaming.
2. Ok here's the thing with CF, i had it for 2 years and i hated it for the most part. For me the CF profiles driver updates wasn't an issue because i dt play games the day it comes out, i ususally buy them months down the line when they are on sale on steam and so by then they already have the drivers for it. But what i hated was the stuttering. You see in the video card reviews they only show you benchmarks which is nice but's different from actual gameplay. I would go for Nvidia cars if you care going to SLI them in the future.
3. Well it sucks because you are a month late in January NCIX had crazy deals. After MIR they even had a PAlit GTX 670 for only $300. Right now i think the best bet would be a GTX 670, it is very close to the performance of an 680 for a lot less.