Ive got some rust forming in both rear wheel wells, to fix it do i just sand it down and repaint it or is there a coating i have to put on it once i sand it down?

 

Take it to a shop. They will properly stop the rust. You can't get rid of rust just by sanding it because it will grow back even if you paint it. you need certain procedures to take care of it, thats why I recomend going to a shop. I would tell you how to do it, but you need more experience in autobody to really do it yourself.