Cleaning / waxing the Class B fiberglass top

I can't believe there are not 50 threads on this. I am embarking on cleaning and waxing a neglected but sound fiberglass top on the 20 year old Class B. I plan to wash first, then use something mildly abrasive to remove oxidation, rinse or wash again, then wax with turtle wax. The abrasive stage will be a testing process, trying a stiff brush, clay-based cleaner, plastic scrubber, abrasive pad, or ?? Any fatal flaw or bad idea in my plan? Any success stories?

Bonus question: sliding glass windows on top are leaking, I have not figured out yet exactly how or why, but a close look will hopefully inform me on that. Any ideas on replacement rubber, sealing techniques, etc?