This is current policy what , gc_chayiye written , which is perfect. If you change your employer you must go for transfering H1, then , you can apply and get for 3 years.
Since you are not going work with present employer, the present is no use even if it is more than year. But it may be useful if you want again come back to your present employer, but I am not very sure about that.
If your 485 application application filed and 180 expired and 140 is approved , you can join new employer by transfering H1.
You can also work with any other emplyer with EAD, provided you no need H1 or H4 for your dependents and most important is you are very sure that your 485 will be approved without any problem.