For the rattle... There are two rubber pieces on the hatch. You need to adjust them out so the hatch puts all the weight on the rubber. Not sure if that makes sense to you but it is difficult to explain. It is a very simple screw adjustment.

As for the radio, get a silver faced blaupunkt radio from crutch field. It is a plug and play. You can install yourself in 15 min by simply sliding out the factory radio (with a key provided by crutch field) and plugging the new radio in. The harness and plug are the same. Real easy. You can read all about this on the forum.