[racer_d]

The ticking sound, at start up, if sublte, is not uncommon on these cars. IF really loud then be worried. Usually just valvetrain looking for some oil that has drained away while the car was not being used.

You might try some solvents, but yellowing, im my experience, usualy can't be corrected. Sounds like replacements might be in order. You might want to upgrade to Litronics if feasible.

"the plasic part in the car cover" ? Do you mean the rear window? again, if not cracked or torn you might live with it. I know some people have buffed out scratches, but not sure I've seen a reversing of yellowing. Replacement might be in your future too.