I'm currently on EAD (PD: 03/2003, EB3,I-140 approved and 485 Pending more than 3yrs now) still with same employer who filed my GC but planning to switch jobs.

Imagine employer revokes my approved I-140 after switching jobs thinking about Pros n cons

1. Notify USCIS with AC-21,they will look into it and approve I-140, even after I-140 revoked by employer Correct??
2. After i switch jobs, I don't have to apply for GC again with new employer and can wait for existing 485 approval as long as the dates are current, I should be approved correct??
3. Does it hurt my chances of 485 approval, if i'm on bench for 6-9 months on EAD.
4. Can you think of any red flags for me in making such a move(switch employers) Let me know.