Don't use to many chemicals. The sun will do the rest of the work for you. I'd be sure to use some conditioner asap after using polish remover.
As far as your buddy goes, I'd walk in the gravel in front of his house and then take a nice stroll over the top his car, making sure to twist around some. That's bs that they did that right after you told them about it. I don't even let people bring their shoes. They stay at the dock, or in the truck. I tell them they don't need them where we're going. I've told people about pens already too. One girl had one in her back pocket. I could just see her tearing a seat or having it bust open. People just don't think. And what's worse, they think your being over protective or "crazy". Those people don't get to many invites.