Re: System Build; I need someone to double check?
1) I wouldn't go with those cheap cards. Get a HD 5450 is you want to be cheap, or a NVidia 9000/8000 series.
2) I think no to both of those questions. Most newer graphics cards use GDDR5, and there are no DDR5 mobos out yet. I believe that DDR2 graphics cards are totally compatible with DDR3 mobos.
AMD FX-8350 Black Edition
ATI Radeon R9 280 x2 Crossfire
ASUS Sabertooth 990FX
Corsair Vengeance 1866MHz 2x8GB
EVGA Supernova 850 G2
Cooler Master HAF 932