Look for a product called "Rust-Mort". You should be able to get it at an Auto PArts store.
http://www.sjdiscounttools.com/sem69508.html
It's an acid based liquid that converts the rust into an inert coating. You brush it on. let it sit overnight then rinse with water. It binds with the metal so the rust won't come back, and acts as a metal primer.
If the "Orange" is original you can get rattle cans of touch-up paint from:
www.paintscratch.com.