That's minor, and on the protective film, lucky :) Get down to toyota and get a new set of arch protector film ordered up. You could try giving it a rub with something like autoglym super resin polish first, but i'm not convinced it would work:)
don't know how people can say that tein basics aren't much better than tein springs, I have the coilovers in my own car and my mum has just the tein springs and altho they do the job for her, they are much much softer than the coilovers and it doesn't handle anywhere near as well as my car. Would definitely recommend the tein basic coilovers. Not sure on the apex fo the yaris but my dad had an apex shock/spring kit in his old golf and BOTH the front springs snapped. Steer clear from Pi as well :)
did u just pressure hose, or hand wash with a decent shampoo too? Petrol will/should shift it but u will need to re wash the car and polish/wax afterwards. A clay bar should also work or a decent tar remover. Again, polish/wax the car afterwards to protect and get rid of any residue