Removing scratches and maintaining the clearcoat and body of car

When it comes to scratch removal, you need to be very careful. What these products do is remove very thin layers of the clear coat to a depth beneath the scratch. Then a polish is applied followed by wax. There are too many scratch removal products on the market to count or rate which is the best. However, the ones that work are usually the ones used by professionals because they know what they're doing. If you apply a scratch remover incorrectly, you stand a very good chance of ruining your paint job. If you cut into the basecoat, that area will forever appear duller than the surrounding area.
The scratch removers not used by the professionals are tend to be the ones that don't live up to the advertisements. As for maintaining your clear coat, that's what a wax does. The more frequently you apply a good wax, the longer your clear coat will stay clear.
If you're sure you want to tackle the scratches on your vehicle, try Meguiars Scratch X because the have a complete product line from scratch remover to polish to wax.

As for your headlights, I really can't explain why there would be a film over the plastic after driving in a hard rain, unless you were driving behind a truck on the highway and maybe some oil got sprayed on the front end. All plastic pieces on your vehicle will eventually deteriorate due to oxidation, weathering and scratching. Meguiars also sells a plastic polish with a buffer that you can use to remove any of those effects as well as a plastic wax to protect them.

Sorry it took me so long to respond to your follow-up question. I've been off line for a couple days. As for the product you choose to use, I only recommended Meguiar's because the make a complete line of detail products from A-Z. Keep in mind, that is only my opinion, and there's plenty of other quality waxes available.

With Meguiar's Ultimate Paste Wax, you do not have to tape off any areas, though that might save you a little time when it comes to removing the wax.

Also, make sure to follow the manufacturer's instructions on the bottle, and that goes for how frequently to apply their products. With all waxes, it won't hurt to apply them more often than what's recommended, but it would cost you money unnecessarily. If you frequently drive on gravel or dirt roads, then you definitely should make an application more often than if you only drove on paved streets. That also goes for if birds like to single your car out as a nice place to use the bathroom!

Good luck.