Hey!
To answer your master volume question, I am a BIG fan of the Lar/Mar PPIMV. It's cheap, easy, sounds great, and when it's full up, it's basically completely out of the circuit, so overall colorization of the sound is minimal. Check out all you need to know about it here:
Lar/Mar PPI-MV - MetroAmp Wiki
I hope this helps you!
-Lane