Eric,
You should try to clean the rust first, most of it will go off easily on the porcelain.
I wouldn't sand and spray paint the porcelain finish. After you'll have removed the rust stains on the porcelain, you'll see it's not that bad and and then you can apply some touch-up paint with a small brush just where the porcelain is chipped.
Also, to clean the plastic liners in the doors, avoid using anything strong. Just warm water with hand dishwashing detergent should do it and it won't damage the plastic.