You should do whatever makes you happy. You should expect to spend 40+ hours plus to clean the playfield, touchup the playfield, clear the playfield and then reinstall the playfield if you want it perfect. Plan to spend a lot more money than you think if you want it "perfect" from a reputable clear-coater. A perfect CQ W?D is only worth so much. If you don't mind losing lots of money on the project, go for it!

It is normal from play. The amount the game will be played in your home will likely never make them any worse. Don't try to fix what ain't broke.

I have an idea of what a nice condition example of this game is worth. I really don't think you can make the example you show here any better or protect it better (besides cleaning it up). It looks great as it sits. Adding mylar would actually complicate things and I would strongly advise strongly using it for this title in particular.