Forgot to attempt an answer on the pneumatic/electric polisher. The Pneu would be fine, if you have a good source of clean compressed air and the pressure can be maintained. I'm not sure if the pneu would have variable speeds, and that would be a deal breaker for me. The electric version (I got the 10' cord model...have plenty of extention cords) has 10 settings and from about 3-7 are useful when polishing the bike...the slower speeds for the orange pads and swirl remover, and the higher speeds for the real polishing part of the process, with the red (softer) pads. It doesn't take much product to get the job done with this tool, it does a better job than you can with your hands, and if you don't put too much product on the pad, or lift the buffer up before letting it almost completely stop, you won't have any slinging of product all over the place. The foam pads are really nice.
There's a couple of other guys on here who have the Griot 3" Orbital...at least one of them had the same, favorable results as I did.