Drywall is an inappropriate material for grow areas, as it is susceptible to moisture damage. Look at Home Depot for metal grate material, and be certain that all yoru electrical connections are very well insulated.
Don't forget that your ballast needs to breathe. This sounds stupid, but it's true- there has to be a way to dissipate heat, or it will fail prematurely, and may become hazardous.
Silence it by placing it on silicone vibration-dampening feet or a sheet of gel designed to be placed under stereo or other vibration sensitive equipment. I know they sell it though edmund scientific online, and probably at higher end stereo component stores.