Activision makes guitar hero
Guitar hero is made by Activision
You can in Guitar Hero World Tour by going into the charactor creator and hit the instrument you want to customize.
Well I hate to tell ya this but it would be very difficult sicnce guitar controllers have very specific signals. If it is a wired one then even more so unless you wanted to make a rig, but that...
On everygame after Guitar Hero World Tour, yes.
On GH5 yes