The frozen donkey wheel is an sctual frozen wheel below the island and must be unfrozen for the island to move. The island can be moved phsyically and it can be moved through time. The room with the wheel is made of ice so is why Ben was wearing a parka in episode 9.
more to come........
Sun believes Jack is the second person responsible for Jin's death because just as the helicopter leaves the island or the freighter (not sure which one) the freighter explodes with Michael and Jin on it and Sun is telling Frank to go back but Jack yells "Do not go back to the island!" because he believes there will be too much weight.