Avast! deploment on multiple systems

I have a few machines here (10). I plan to install avast free on them, I would like to know A: Is it legal for me to do this? and B: I need a way to turn off both the sounds that it makes and a faster way to get the key entered into Avast (without having to type it in). Sort of like a Batch file to copy the .dll or the .ini or whatever that avast uses to register and a registry key the will turn off “Avast Sounds”.

Any help anyone could offer would be very much appreciated.