It's hard to tell for sure because your camera isn't well focused, but based on what I see I would choose to polish it carefully with carnauba wax rather than clearcoat it. Once the game has a nice very nice layer of wax, you've considerably slowed any further damage to the paint. Then you can take your time planning a more perfect restoration with clearcoat in the future.

Maybe in the future you'll have a better opportunity to clean out the cracks without damaging the playfield. Anything you do to clean out the cracks should be followed with an automotive clearcoat as vid1900 suggested above. If you're going to use sandpaper on the playfield, I believe 600 grit is too rough. If you can find a store that sells auto-body materials, they should carry grits of 1000 and up. Using 1000 grit I can clear the high spots, and then follow-up with wax and get a very high gloss finish.

Magic erasers with alcohol seem to be the best approach for micro cracks/ball swirl marks. Be very careful, and very patient. You still might not be able to get the area 100% clean, but you should be able to get at least an 80% improvement.

There's more detail here:
http://pinside.com/pinball/forum/topic/magic-erasers-and-ball-swirl-marks

Wear close to the inserts is often caused by the insert either raising or lowering and creating a step for the ball. If that's happened here, make sure you fix it before you paint or the wear will return.

Come to think of it, you might want to read through this whole thread from Vid and then come back with questions.
http://pinside.com/pinball/forum/topic/vids-guide-to-ultimate-playfield-restoration