to a): there seems to be no need for a special swap move. Instead move the King / Queen to the Bishop of opposite colour, which seems to be an impossible exchange, which should be skipped then.
Initial exchange moves (of traditional sequence: White starts) could be integrated into traditional game notations by starting a game at a negative move count (here e.g. -2 half moves), supplied by an appropriate FEN. But I am not yet convinced that an intended relocation would be better than a randomized one.