[89IROC&RS]

as far as the paint chipping, well, that kinda happens, personally i was my car by hand for that very reason.

as far as the water leaks, i first and foremost look to the T-top weather stripping, but you should have a bodyshop pressure wash test it for leaks, or get in it yourself, and have someone spray water around all the cracks and crevises to see if you can tell where the water is coming in.

as far as the tail light, i suggest buying a new housing, the drill hole let the water out, but can let moisture in, and causing the problem to come back again.