Am also interested in the answer , my wife’s Rav has yellowing headlights so I need to tackle them too!
One of the best "off the shelf" kits I've found is the Autoglym one, I just use my cordless drill, it's a Makita but any decent one will do the job as you need a reasonable amount of time to achieve good results. The AG kit has waaaay too much polish in there for the amount of discs you get so I have just been topping up my stock of 3" sanding discs over time, recently I bought some assortment sets on eBay which go up to 4000 grit but I don't think they are any better than the trizact ones in the kit. What's that old adage? Buy cheap, buy twi...
Here's the kit,
Headlight Restoration Complete Kit shop around for a good price but for what you get, £28 is worth it as you'll be able to do several sets with some top up discs.
I don't bother to seal them with anything other than a wax polish. Some people lacquer them I understand but I feel that you need a flawless finish and when you've polished them that much, what will the lacquer key to? I'd rather just buff them with the pad and some of the polish every few months personally. The lens is thick, you'll never go through it like you would paint.
One update on this would be that I have both headlights now and have fitted an HID kit to the projectors. I knew that fitting these lamps would cause me to lose the fog (or W**ker) lights from the front of the car but that's no loss to me however, I wasn't prepared for Mercedes to use the same plugs but wire the headlights differently internally. That was a bit of fun to work out!
I haven't been out in the dark properly yet though as I found a split CV gaiter on Sunday so I'm not driving it until that is fixed as the mess will be horrific!
Here's a test that I did in the garden to ensure the beam pattern was ok and had a nice sharp cut off line. It does of course, they're projectors. .