Visa transfer in India


I have a H1B,that is valid till July,2018.But due to some personal reasons im not able to travel.I have travelled for one year(Oct 2015 to Oct 2016) from the current company. Now,Im thinking to change to company from A to B. Im getting below questions.

1.Is it possible to transfer H1?If Yes,what is the procedure and documents needed?

2.What will the current employer does with H1?

3.Can it be transferred even after the expiry?

4.What is the total cost incurred in transfer?

I would be happy if i can get the answers.