Hi Craig,
Metal or plastic
If it's swirled, I suspect it's painted metal.
The easiest way to determine this is to use an ordinary magnet. Try not to use a strong one because I suspect there's metal in there somewhere...
Use the Griot's 3" polisher and start with a White foam pad. Apply some Wolfgang swirl remover to it and do a test spot and gauge your progress...
Headlight and taillight lenses should be cleaned and polished not only to keep them looking new but to also ensure that they stay clear and bright...
Take your time and don't be too aggressive until you're used to how everything works together then step up your game....