yes they will
i would get a faster cpu, because the gpu you chose is quite powerful, ut his maximum potential in terms of frames per second can be reached only if the cpu also pushed as fast as possible, the fx6300 is not strong enough to make full use of the r9
so for example, instead of get 100 fps on a game, perhaps you will get 70 or 80 fps
nothing terrible
what psu are you going to buy for that gpu, you need good psu, 500 watts minimum
if you can get 16 gbs of ram, in a good price, i would get it, if not, a 2x4 ddr3 1600 or 1866 will be great