Need a sound card, no, not unless you are a audiophile
Get a CPU cooler like a CoolerMaster EVO if needed for OC'ing, otherwise the stock cooler will get you to nearly 4Ghz on air.
Yeah, you could get that board, don't see why not.
Could get this for a little more;
Video Card: PNY GeForce GTX 760 2GB Video Card ($236.98 @ Amazon)
Or I guess an R9 270x for $10 cheaper then the one above. Right now I suggest GeForce for almost anything over $180 ish
I get a little flak for that though xD
Texel rate is better on the 760, pixel rate is better on the R9 270x, I'd still go 760 though.