I have some outdoor metal chairs that have a few rust spots and the paint is chipping in a number of places. I'm looking for the best way to clean off the rust and paint so I can repaint them.
They make spray paint designed to go on "right over the rust". A wire brush to get off any loose flaking paint and rust, then spray away. Rustoleum is one brand, but basically if you go to the hardware store, find the paint area, then look around for shelves full of spray cans, you will hit the jackpot. Read the label to be sure, but if the word Rust is in the name, generally you don't need to strip the old paint and you don't need to worry about rust that isn't forming large flakes and half falling off.
You could use a grinder with a heavy grit sandpaper to remove the paint and the rust. If the rust is not that deep, you might be able to use a pressure washer with a high psi nossle. That will remove the paint and loose rust spot very well. For the spots of rust that are too deep, you might be able to use a rustolium primer to paint on it first after the cleaning then paint it.