When polishing and waxing the paint, would it be good to go over the headlight also? I noticed on the PC DVD that they buffed the headlights with the PC. They were glass headlights though. All my past cars headlights eventually turned a nasty yellow. It would be good if I could prevent that.

 

Older cars used cheap plactic when plastic headlights first came out and that is what caused the lenses to turn yellow esp with HID lamps. My old 2003 Maxima that did the same thing nad I sanded and buffed them once a year. New cars have a different / better plastic that does not require as much maintance to keep clean / clear. (More UV restistant)

You can always clean them with plast-X or 3m platic cleaner and polish with a PC polisher or a DA with a sponge type pad. Just never buff them with a whool pad on a buffer or you will heat them up and burn / melt the lense.

If they are really bad (Foggy, scratched, yellowed, pitted) you can wet sand them starting with 1500 grit and work up to 2000 and 3000 grit and then use plast-x with a PC polisher or DA to polish them up.

This is what I use:
Porter Cable 7424 XP Variable Speed Polisher $120.00

http://www.autogeek.net/porter-cable-7424xp.html