Here's what Kevbert means when he says rivets don't like sanding: rivets have a little dimple on the head. If that dimple is removed by sanding, the rivet is considered no good, and needs to be replaced. I've seen planes fail pre-buy inspections because someone went wild while prepping the plane for paint.
As you probably already know, polishes contain abrasives designed to remove oxidized paint. It's common to remove the oxidized paint, halos left from bird poop, and bug residue using a polish, and then follow that with a wax.
A shop that sells automotive paint and detailing supplies will have a broad range of polishes, from very aggressive to very mild. You could buy a range and experiment to find the one that works best, but be careful: the paint on the upper surfaces will have oxidized the most, the layer of good paint will likely be very thin, so it will be easy to polish right down to bare aluminum.
Be very careful to keep the polish off plexiglass. Some polishes contain solvents that will react with plexiglass, and you don't want to create a second time-consuming chore!
Waxes (true waxes) don't contain any abrasives, so they aren't designed to remove oxidation. However, on badly oxidized paint the action of applying and buffing off the wax will definitely remove some of the oxidation. You can skip the polishing step and go right to waxing if you like. On badly oxidized paint you won't get a super shiny result, but it will improve the looks. In my experience if you skip the polishing step the wax doesn't seem to stay shiny as long, so you might find yourself waxing again sooner than you'd like.
An electric or pneumatic buffer will definitely speed up the chore. Don't spin it too fast, be very, very careful working near corners and edges (where it is very easy to remove all the paint), and don't bear down too hard. With a buffer you will almost always create some bare spots - it's almost impossible to avoid.
After buffing off the oxidation be sure to follow with a good coating of wax. The final step is to carefully remove the excess wax from the creases and crevices, a task that seems to go on forever.
Detailing a plane is a long, tedious job, but it is rewarding when you step back for a look and see the whole thing shining like new!