approved H1B visa and petition A employer travel on B company petition


I am having approved H1B visa and petition from my current employer but they donot have any project and currently i am in India.But employer B is offering me job in US and ready to transfer my H1B petition and he is telling me to travel to US on current employer visa.

So my question is

1)Is it valid to travel on current employer Visa to US and work on B employer petition.

2)Will my current employer can cancel my visa once i resign.

3)What are the risk if i travel on current employer visa and work for B employer

Did you travel with employer A visa and worked for Employer B?

Was there any clarification at port of entry?

What questions did they ask at immigration?