depends really how bad the swirls are tbh..if reallly bad could try MP'ing them or use some AG car polish/fast glass
as for plastic light fittings not sure tbh...
Problem with plastic clear lamp units many are coated (on the outside) with a UV protection (to prevent the sun light turning the lamps yellow) you can do it however you need to be aware of that first a good sealent with UV cutting property's will help reduce any uv degredation....
hmmmm my windscreen is pretty poor tbh wipers have marked it etc. is there any way to get round this without a polisher or would a dirt cheap one work well enough for these purposes?
hi if you go to machine mart they have a glass polish kit that works they also have the uv coating to reaply once the plastic has been buffed hope this has helped
martyn