If you are doing auto body rust repair by replacing body panels, you will need an air-driven chisel for rusted bolts and nuts. A high-speed wire wheel, a good drill, tipped with a slightly undersized carbide tip to drill out any remnants. Line up any holes, drilling out old screws, use sheet metal screws to secure body parts. You will also need a good paint sprayer. To repair a panel: remove the tops of any screws on the current panel. Drill out the remains, using the slightly undersized drill tip. Next, remove the old panel and line up the new one, tightening it down with flat-headed sheet screws. Clean the parts, prime and paint them.
For more info, see Lower Your Auto Body Repair Cost: What Can You Do Yourself