I came to USA on F1. Then I found a job and got a H1 visa. At the meanwhile, I worked on my dissertation and kept enrolling (I registered in dissertation writing this Fall). However, I did not do anything when 1-20 expired in 2009, because I had a good H1 visa. My H1 visa will terminate the end of this year. As I have not completed my dissertation, I want to go back to my F1 visa to keep my legal status. My questions are:

1. Is my case qualified for I-20 extension or issuing a new I-20?
2. Will such a request be denied by USCIS?
3. How long will it take for the process?
4. If the approval is made after my H1 expires, do I need to leave the country and then re-enter?
5. Can a lawyer on my behalf work on I-20 renewal if my school's international office can't do it?