All DDR3 will fit the board. Most MB makers also have a QVL(qualified vender list) for memory, but most 8 gig sticks should work fine. They tend to have slightly lower timings(like cl10 vs 9), but it is not too much of a problem in the end.
2 sticks should also have the advantage of placing less load on the memory controller and many times you can get a better command rate timing(for all the good it does outside of benchmarks)
uhhh, it should. 240 pin is common ram and that should compatible with your mobo. Mind if I ask why do you need so much ram?
Ram is cheap
I have the same thing(well G-skill).