1 mobo is great! I've got essentially the same board w/o the builtin vid card.
2. 2 256 chips is best! Put them in slot 1 and slot 3 for Dual DDR action.
There were some issues with RAM on this board and somebody got me a link to it.. can't remember where it was now.
Myself I use Crucial memory (256x2) and it works great
For cooling I just use the stock HSF (not overclocked) and it stays a very nice 40C at full load!