Caliper is a sperate item to the hanger and brake pad clips, so even if the caliper is rust free, you may still have a rusty hanger that causes the brake pad clips to become tight on pads movement, you will be removing the caliper so worth a little time to check and clean the pad clips up and copper grease, when done, you can get new pad clips if originals are rusted up so they prevent free movement of the pads, though still have to get caliper sorted judging by your photo .