I had a version of this module and I recall there was one additional cable for another pad. i suppose this pad could be a kick, or cymbal.
I don't remember the kick switch, but I'd guess that it allows the kick to trigger from a switch or a pad. With a pad you'll get velocity.... and could potentially have a double kick if the pad was large enough to accomdate two beaters.
As for surge, yes you can, but only single zone.
Hope that helps. Although, I could be wrong, as the DM6 I had was sightly different.