Chuck- We have our own polishing compound that was developed locally for the big rig industry which is the best we've found. You can e-mail Kris@roswellwakeair.com
and he can hook you up with a kit if you're interested.
This polish is a granular liquid that goes on with a cloth. Let it dry (a minute or two) and then use another cloth to take it off.
As far as protecting the finish goes there arean't a lot of options available- We've tried anodizing the polished aluminum but found that it really dulled the finish and took away any "chrome" look- The best bet if you want zero or nearly zero maintenance would be to find a quality powdercoater who can clear powder coat. They should be able to show you a sample of their work and you could decide if thats a viable option.