Body and Paint Questions

High spots, in your situation, would only be known if you were actually block sanding the car to begin with.........by that I mean flat blocks or boards that would first expose high spots.

At this point, the guys make good points here.....You should remove the paint (by whatever means you choose.....some guys avoid stripper because of the mess and toxicity)....THEN spray a good quality epoxy etching primer surfacer........Most areas in need of body work should be plain, but blocking the car (block sanding with a 180-220) will expose all of your problem areas that would ruin your paint job if left unattended.

Do NOT hand sand or use a "DA" or random orbit sander at this point....use FLAT BLOCKS or boards available at any body repair outlet, with the proper paper. You want your car flat, then use something flat.