Opinions of new rig please!

[scotchegg]

This is the set-up I'm considering:

i7 2600K, Thermaltake ISGC100 fan, ASRock Z68 Pro3 MoBo, 8GB DDR3, XFX HD6950 (2GB), Zalman Z9 case, Win7 64, 720WPSU.

1) Is it easy to overclock with this CPU / Board mix?
2) RAM seems fairly cheap at the moment - is it worth paying a bit more for 16GB?
3) Is that a good card? (And are the blue lines on the horizon finally fixed in COD for HD69 cards?)
4) Is 720W enough power?

This'll be mainly for COD and FSX. Any opinions much appreciated!