I have a priority date 10-4-2007 on EB2 from company A.I have changed the employer from Company A to Company B in July15th 2008.I got approved eb2 from company A on Aug2008.Now Company B has filed I140 on Eb3 on June 2011 and still it is pending approval.they have applied to Port the Eb2 Priority date of company A.
I have an offer letter from Company C and I want to take it as they have said they would file in Eb2 Quickly after I join.I am on 7th Year of H1B till may2014.Now eb2 has become current and I am in a dilemma.

Question1:
1.If Company B Eb3 gets approved will eb3 port will applied over EB2.What are the pitfalls.
2.I am asking Company A to file 485 as a future employee as my wife also works for them.Can they apply on my behalf as I left company before 140 become approved.