I am going to change my own brakes soon, and have some questions about cleaning the calipers.

1. is it OK to spray brake cleaner all over the piston? will it damage the seals, or any other rubber part?

2. before pushing the piston back in, what should I use to clean it? I think there is some corrosion on the piston itself. Do I use sandpaper? I don't think it is a good idea to push a dirty piston back into the caliper.

THANKS!