Regarding the scratches, i suggest you don't do it yourself. If your car was a generic white or black, I would have given you a link for an easy paint job for less than $50, but your car's color would be hard to match.
CAI is basically a Cold Air Intake. Instead of your car's standard air intake, it's a wider pipe, and it allows more air and colder air to go into your engine's combustion chamber. Colder air means potentially better combustion, and probably higher fuel consumption (although it may not be THAT much, mind you)
I know you can get normal aftermarket intakes from any auto shop for about a 100 dollars- K&N and AEM are the most frequent brands.