My suggestion for the combat rule would be to have all combat through RP, turn based, with a limited amount of turns. That last part applies only when it's a one on one situation. I only suggest this because a lot of RPers I know aren't interested in the PVE (leveling) aspect of the game so their characters might not be high in level and it's not fair to have a character with reasonable IC skill lose to another just because they are higher level.
Though I suppose if they dueled in RP gear (most of which has little or no stats) and limited them to a few skills that make sense for their character's combat background it could be fair.
Though I suppose if they dueled in RP gear (most of which has little or no stats) and limited them to a few skills that make sense for their character's combat background it could be fair.