Auto body repair & detailing: Bumper Paint Repair, grit sandpaper, paint repair

Question
On the rear bumper of my recently purchased 2000 Volkswagen Golf there is a small patch where the white paint has been scratched down to the black bumper.  It looks like someone accidentally backed into some rough concrete or something and scraped it.  I know that it will cost me a bundle to get it fixed at a shop... how can I fix it on my own?  Also, there is a tiny spot of superficial rust where the paint chipped on a wheel well, probably pretty recently.  The spot is about one third of an inch big.  Can I use regular heavy grit sandpaper to get the rust off before priming and touching up (it really is just barely rusty) or is it essential that I use a grinder?  Thanks so much for your help!

-Liz

Answer
I would go to your local auto paint store and have them make you a little touch up paint and dab in on your affected areas. It will look pretty good if you take your time in doing it. If you get into sanding the finish you will making a big mistake for you will have to after wetsanding prime, seal.paint then clearcoat the entire panels. Not to mention masking car for overspray.And finding a spray gun and compressor.
        Hope this helps
                       Brian