Re: Building new kit from scratch (Yamaha based)
Custom kits are highly personal. I recommend staying with an off-the-shelf, out-of-the-box Yamaha kit like a DTX-700 or DTX-502 (if money is tight). It will be better for the different drummers who sit-in, given your situation as described.
Yamaha DTX drums, DTX700 module, DXR12 sound.