4" pads will work in those areas. The PC doesn't have enough power, nor does any free spinning DA polisher, to damage your paint. You would only damage it if you beat it on the car. The trick is to keep the pad rotating so you can remove defects. This video should help you out. As J Truck already stated, do a small test spot on the newer clear, and adjust if needed. This video may help you if you haven't seen it already.