My setup:
On panel: Pause only (both players, next to p1 / p2 start). Shifted function - Esc (p1 start + pause)
On top of cab: Tab (shifted with p1 start = F2 settings), in Mamewah it's shutdown.
Under panel (flip up front): Coin, Reset, Lightgun cursor
Soon to be added under panel: Save state, load state