Can I change employer after I140 aproval-I485 not applied

[desi_kallu]

My I140 was applied by my current employer. Can I change employer after I140 approval. After going to new employer Can I still keep the priority date of this I140 (actually Labour, which is OCT'2003).

mine is a Typical case
1) employer A filed labour in Jan'2004. Still pending in BEC, not with drawn.
2) Employer B filed PERM. Not yet approved.
3) Employer B file I140 with sub labour.
4) My 6 years expire by June 2006.

Questions
1) Can I get 7th year extension from current employer? if yes How I can get?
2) If I get 7th year extention. And if my I140 got approved, can I apply for remaining 2year extension?
3) If I get 7th year extension and I140 got approved. Can I change employer and keep the priority date of I140 with the new employer.
4) If I want to change my employer NOW...NOW...NOW...NOW. What are my options
a) H1 transfer with 7th year extension. (20 months)
a) Apply PERM labour--minimum 6 months (start adds now..etc)
b) Apply for I140 should be approved with in 14 months. Then I am eligible for further extension.

If I am wrong any where please cover me.
Other than this any other better options left for me.

United Nations/Guru..and all immigrant intilligent people, kindly advice me.