As I see it , your best option is to apply a first layer of clear coat ASAP .
The remaining glue will disappear under the clear coat. raised areas from the glue or cracked paint will even out after you wet sand the playfield.
Make sure though you wait a week after the first layer of 2pac before assessing the job.
Leveling the inserts can be done , along with the first layer of 2pac.
Since the problematic white areas are yellow , you will need to reapply white , so the damage will disappear anyhow.

If there is prominent flaking , obviously it should be removed before applying clear.
But airbrushing a bare playfield before locking everything with a protective layer of clear is , imho , wrong. Making a mistake is difficult to correct. Also “hills and valleys” not filled with clear before airbrushing , will be prominent under side lighting.

In agreement with Blake regarding naptha and Novus. Naptha will not really clean troublesome areas , but Novus 2 might. Go slowly and watch for paint on your white microfiber cloth.
As for areas not holding up to clear , unless you get flakes flying around by just blowing some air with your mouth , which it seems is not the case here from the pics shown , applying clear is completely safe and mandatory.
Dealing with a very neglected playfield that makes yours look like new , the first layer of clear , made all the chips and cracks disappear. I had to repaint all the playfield though.
https://pinside.com/pinball/forum/topic/surf-champ-slow-playfield-restoration#post-4720407