I came to US on H-4, so I have only H-4 stamping in my passport. Got my H1b picked up in lottery two years back, and did COS to h1, and have approved i797A with I-94 and working with my current employer.

Got an offer from another company, and they filed my H1b transfer, and got the i-797A approval with I-94.

So my question here is, can I join the new company using the H1b transfer approval, even though I don’t have H1b stamp at all in my passport? Will this be a valid H1b transfer?, or should I go back to India to get my H1b stamping to join the new employer?

I am planning to switch from Employer A to B. Can you please help clearing some confusion i have.
Moving from Employer A to Employer B with I-140 approved.

1: If Employer A revokes I-140 and Employer B files a new petition I can retain the priority date. Does Employer A have to revoke I-140 or if he can continue it even if I am not working there?<br>
2: If Employer A doesn’t revoke the I-140 and Employer B files a new Labor and I-140 petition and retains the PD of previous I-140, would the previous I-140 be valid anymore?<br>
3: If Employer B files a brand new PERM and I-140 with new PD (2020) and Employer A I-140 is valid with the old PD. What happens if the old PD becomes current. Do I need to go back to old employer A or Employer B can file I-485 with the old I-140 PD.<br>
4: Is there a one year max limit rule on filing the I-485 once the date becomes current? What if it cannot be filed, does that void approved I-140?