Easy rust removals;
There's a liquid that's called Rust Convertor. Comes in a liter bottle and is light green in color. You should be able to get it at any auto paint store. Apply that to the rusted area and leave, the rust is converted to powder form and vanishes. After that you can either have the area covered with WD-40, grease or harder primar.
You will get all these things, original from the right hardware / auto paint stores.
If the affected area has developed holes, then I'm afraid that area is beyond repair & should be replaced.
Rust is the cancer of metal, treat it timely & you'll stay happy.
Hope this suffices your queries.