1) If my current employer does not revoke I-140 after I leave, can I file I-485 if my future job is a similar job as my current one?
as far as I know:
---if you are on H1b now, you got to find a new job asap and transfer your H1b. if your current employer won't revoke I-140, technically, you can file 485 once your PD is current, then after 180 days, you can file AC21 to change your sponsor. Employment based GC is for future job, as long as your I-140 is approved, that means your sponsor is willing to hire you permanently. if unfortunately, USCIS made decision before your 485 case is pending 180 days, then your current case is dead, you will have to file another PERM and 140, but your PD is still good.