I-140 Approved with Company A and Moving to Company B - Consequences

[samirshingle]

Hello All -

Here's the situation -
I have an approved I-140 from Company A and plan to move to Company B.
While I am aware that the H1B can be transferred from Company A to Company B, following are the questions I have with regards to Green Card process -

If Company B does not sponsor Green Card application, can company B extend my visa after my current visa is expired in 2015 (H1B will be transferred over to Company B)?
If Company B can extend the H1B application, then is there any caveat to it ?

In order to continue the Green Card application process, does Company B need to redo the PERM application and so forth?

Are there any other consequences / impact of such a move that I need to keep in mind?

Assuming it might take few more years prior to my priority date getting current, (unless the uscis proccess applications at a greater speed), my goal is to pursue job opportunities with other companies until the time comes close to getting priority date being current which is when I can think of finding an opportunity with a firm who is truly willing to sponsor GC.

Appreciate all the help in this regard.

Thanks in advance.

Sam