Damn, that sucks to see! And it was real stupid of her to run off if she goes to the same school as you... because you are guaranteed to find her. I would press charges because people need to learn that they need to be accountable for their actions right away, instead of just "if they get caught". Better for her to learn the lesson now than when she's older and in a far worse situation. At any rate, she should be on the hook for the new fender and paint. You can always work things out outside of court but you shouldn't let her get away with it entirely.
I was 'lucky' in that the guy who hit me felt absolutely terrible about it and was a good upstanding guy. He called his insurance, told them it was his fault (it was), and they paid for everything. It was a much pricier repair than yours will be because he rear-ended me going 40 mph faster than I was going, which did about $22,000 of damage. But, his insurance paid up, I was made whole, and I doubt that his insurance really went up that much considering it was a first time offense.
Yes, they are EXTREMELY common as a lot of people don't have insurance... or morals. Or both? The worst are pedestrian hit and runs.