I-140

[lathaS]

1. I am working in Company A with whom I got my H1 Approved for 2 years.
2. I am worked in company B for past and they applied for I-140 (on August 2018) and got Approved in feb 2019 .
3. Now for a client company which I am working with company A they said that the client wants to offer me the full-time position after 3 to 4 months

Questions:

1. Company B wants to transfer my H1 to their because if I-140 gets approved then they are saying I need to work on their payroll or else they may revoke my I-140, Is it true ?
2. If I-140 gets approved with company B , without revoking it how many days they can keep without transferring my H1 ?
3. Can I transfer to the company B with H1 receipt, is it good to transfer on receipt now-a-days?
4. Please let me know , without revoking my I-140 how can I stay with company B 
5. My job roles will be different , when i-140 applied by company B the job role is software developer , if i transfer my H1 from comapany A to the company B then the job role will be different (Zendesk developer) ? will that affect i-140 approved one also ?
6. Now, i am in a situation where i don't no what to do , please kindly reply to me .

Thank you