What sort of commercial systems have you done in the past? The bulletproof nature of a lot of those components, in comparison to home components, places them in a different world. Also, they almost all use three-prong plugs, which means that grounding issues can be totally different and weird in a commercial situation. Add to that the fact that most of us who have done home systems have no clue about microphones and feedback, and I hope you have an idea what you are getting into.

I have been involved in audio and video since the early seventies, and because my focus is residential, I would call on a friend for this information, and maybe to source and supply and yes, make the profit himself on the components, in order to be sure the right stuff was used. Here's how serious I am about this: he started out as a car stereo installer and I taught him residential. I taught him a lot of what he knows theoretically, and even helped him with a troubleshooting problem last week. But he branched out into commercial and now does almost exclusively commercial work, and I do residential, so I would bow to his expertise and not expect good enough or thorough enough answers from him without his being involved in the deal. You will get some very good information from others on this site, but my feeling is that you will spend A LOT of time getting this right so it might profit you to locatge someone who specializes in this area.