My understanding:
(1)You may not receive RFE and get 140 and 485 approved, if you are lucky.
(2)Because you can change job after 180 days, you can work for other employer after your 485 is approved.
(3)If you get RFE for 140, you need to have a full job at that time, so you can tell INS you have changed job after 180 days.