I'm very new on this site as well. For the smell a carbon filter should do the trick. I also heard about a can of gel that will remove smells also, can't think of the name right now. Depending on the size of the amp, one out-take fan should be enough. The other air should come back through just from passive intake, if the negative pressure seems to much you could always have one intake fan. Your lighting though, I would suggest to get at least another one of those cfl's, it would do wonders on your plants.