In post #2 you chose a GTX 570. Now you've selected a GTX 460 SE? At least spend $30 more and get the regular GTX 460.
It overclocks like crazy and stays pretty cool. I've got mine up to 875 core, 1000 memory, 1750 shader @ 1.0v. I could definitely push it further if I wanted to. MSi Afterburner (included on driver disk) makes overclocking very simple. The temps hit 69*C in Furmark and never go above 60*C in games.
Any of the RAM listed will be fine. Might as well go for (3) since it's the cheapest. That's the RAM I am running if it makes you feel better.