IF You have the Tools, or Access to the Right Tools. Do It right Now, you wont regret it Later. You say You are just starting to Restore the Car.
1st of all if this is your first attempt doing Rust Removal, Don't be afraid, Educate Your Self on how to do It Right the First Time, 2nd Don't be Afraid, Think Twice before you do anything.
Remove the Door, make a Tank an follow the Process in the Link, Below. It will Remove the Rust Cheaply, and Paint too. Then if you have Access to a Sand Blaster, Gently clean off the bad spots, the Tanking didn't Removed. No Blaster, use a 4 1/2 Grinder with a Flat Burred Brush, Not the Cone Type, the Flat Notted Wheel works Best. The Grinder can be a cheap one from Harbor Fright or E-Bay.
After all the rust is Removed, before it gets a chance to rust again, Spray or use a Paint brush. Apply Phosphoric Acid to all Surfaces to Prevent Re-Rusting, when Dry, Prime. Phosphoric Acid can be Bought a Ace Hardware or most other Pain Stores for $24.00 a Gallon.
If you don't want to do this process, just brush onRust-olem, better than Nothing?
http://www.davidbradley.net/ERR.html
http://www.harborfreight.com/power-tools/grinders/4-1-2-half-inch-angle-grinder-95578.html
http://www.harborfreight.com/4-1-2-half-inch-knotted-wire-wheel-91279.html