looks like some sort of luff tensioner?
as for light air, weight position is a little screwed up by the skipper/traveler rule. leeward heel and crew up at the shrouds, even putting some in front.
mast should sag to leeward upwind so 2-3 steps down from base tune is good. also, I find putting the boom above centerline in the light helps power the main up.
downwind, hold the boom so the kite gybes first. once filled, gybe the boom over. this helps come out of the gybe with speed. this is tough crew-wise in light air as you really don't want weight aft