job change when I140 eb2 approved. also keep old priority date issue

[srirambhakt]

Hi,

My employer A is not willing to give me i140 approval receipt. I have receipt number and an email from employer A that as a company policy they don't provide these approval notices. my questions:

1. Can I still get 3 year extension when I transfer My H1B to company B.
2. I want to keep my priority date when i file GC wid my new employer. How that can/will be possible?

Thanks.