The factory preset "Knife Fight" accomplishes this by assigning the output block's level to snapshots. You could try that approach. As to your other problem, try turning on Discard Edits and see if that fixes it.
I see what you're saying. Since a Gain block takes up very little DSP, you could have 2 with the same settings and assign one to Stomp A, one to Stomp B.
Are you barefoot? If capacitive touch is enabled (which it is by default), a bare toe will kick you into command center. You could try turning off cap-touch (global settings - switches/pedals) or putting on some flip-flops