a !teleportwarden wouldn't be difficult, you'd just need to get the warden's position once it's executed and teleport every player that is on the TEAM_GUARD (or whatever it is) to that position.
I don't think an !opencells command would work simply because the MAPS are what opens the cells, not the game mode. Adding on, you can't really prevent the doors being closed since yet again, it's map controlled.