Question one; I can't answer as I don't have a crew of any description (Unless 20 Marlboro lights count)
Question two; When it's windy I stay very high after a tack until I'm safely out on the wire and then bear away to a proper course. In medium winds when I'm not aiming to roll tack it's beat to beat or as close as I can judge it. In light winds I don't move across the boat until it has tacked completely and has started to make headway on the new course. slightly lower than normal as the main has been dropped off, the new windward hull often lifts and at this point I'll move over (mainsheet at the ready just in case). I find using this method of tacking doesn't upset things as much as moving over when there is no wind in the sail.