i have 2 very small patches of rust ad the tip of the left and rigth doors and some small paint chips on the front bar,

what would be the best way to remove the rust and return the cars colour in the chipped areas? >>

the car is white

Basically grind it down to bare metal till all the rust is gone. Then get this stuff that turns rust into primer. It stops the oxidation through a chemical reaction, its like rust stopper or something like that. put that on and you may have to fiberglass over top of it, then primer and repaint. Or just get new doors.