Can you divulge 2 command cards at the start of setup? Or is there only one "opportunity" to divulge a command card.

I have this crazy idea of using Cad Bane and Darth Maul together...

You can divulge both. Mauls divulge card is explicitly written in a way that both can be used. As long as all prerequisites can be fulfilled (discard the one, play the other) it's fine. That might change in the future when there might be multiply divulge and play turn 1 cards in the same faction.