India
B. Commerce 3 yrs
MBA

USA
MS - Telecom Mgmt
MBA

Working in Comp C
EB2- I-140 approved from Comp C. PD of Mar 10
6 yrs H1B expired on Jul 11. Got 3 years ext till Jul 14

Got an offer from comp D but they will start my GC only after 1 year.

1. If my current emp withdraws I-140, will I be able to port my PD of Mar 10 when comp D files my GC?
2. If my current emp DOES NOT withdraw I-140, and my Perm or I-140 gets rejected when comp D files it, can I go back to comp C or a new comp E and get 3 yrs H1B extension?
3. When comp D files for GC, the job will have a req of 4 yrs Bachelor's degree+5 years exp. As my Bachelor's degree is only 3 years and from India, will it cause a problem? Have Masters from US
4:Iis it a good idea to change companies now?

Thanks