The car bending is probably caused cause you selected parts of the vehicle while naming the parts of the gun. otherwise there could be no influence.
you sure that revolving thiingy is a real command? i've never seen that one before in any other addon.
to the wheels not touching the ground, in 02 the horizontal red line in the fron and side view indicate ground level, so if you want your wheels touching the ground you gotta move the vehicle down so that they do touch the red line. don't forget to readjust the other LODs!