I am in my OPT period till June 2009 & got my OPT extension approved till Oct 2010. My current employer has applied for my H1B in March 2009 & is approved. Also, my current employer says he has my H1B approval notice, but hasn't given me a copy of it or documents. So please guide me accordingly.

1) Can I cancel my approved H1B, & shift back to OPT or F1 (by getting into another Masters program)? If yes, till when do I have time to cancel or postpone my H1B, and what is the process and documents required?

2) Also if I cancel my approved H1B, will it have any negative impact for now or in future if I again apply for H1B? Will I be subject to lottery again for selection?

3) If I get a new job, how long will it take to transfer H1B and what is the process and documents required?.