If you have a lot of dings in it that you don't want to have transfered to the steel you can grind it with a hand held belt sander but I would not worry too much about smaller shallow dings unless they become a problem. Rust will just hammer away. I wouldn't worry too much about the edges either. A picture would give us a little better idea of what we are dealing with here. I would recommend posting one if you can.
Doug Lester