For light rust spots I have had good results with Turtle Wax Chrome Polish and Rust Remover. Apply as directed with a cloth patch, when no more red/brown color rubs off onto the patch, the rust is gone. Touch up the area with a cold blue. This stuff has a very fine polishing compound in it and takes a good bit of rubbing before removing any remaining blue.
I worked over a Model 58 S&W that had a bad case of " freckles " and light surface rust ( went over it three times ) and was just amazed at how good it turned out. The secrete is to go slow, be gentle, work over small areas at a time, keep an eye on when the rust is gone-then stop. After the rust has been removed do not keep rubbing because you will start removing blue.
Whatever you do DON'T use any power tools or polishing equipment on it, they take rust and blue off before you can blink.
Good luck.....Gary
PS The best stuff for protection is something like Birchwood Casey Rust Prevent it was called Sheath but it might be called Barricade now. It has a wax film in it so it doesn't evaporate or remain greasy or oily. Actually a good automotive paste wax does a fine job of protecting, makes guns look good too.