Mark Mandell - Gone Round In Jersey
1st. Question: Yes. Apply 2 light coats of dewaxed shellac, sanding or synthetic wool lightly between them to catch and raised fibers.

Rinse the gun with fresh DNA, then put in a half cup of water and spray that to get rid of the alcohol.

2nd Question: "PolyAcrylic" is primarily a brush-applied product. You'll get much better results spraying with General's waterborne High Performance Polyurethane or their Enduro Clear Poly product.

3rd Question: To clean the gun after the final coat of the top finish, rinse it, inside and out with running water, then fill the cup half way with water and a drop of dish detergent, close & shake well, spray it all out, do final rinse with clear water. Should be all you need.