Atfirst, I came to US through L1B from Employer A in Mar 2006 and stayed till Jun 2007. Employer B filed for H1B in Apr 2007 and got approved as a Indian consulate stamping petition. Again in Sep 2008, I got a new L1B from Employer A(since the old L1B expired) and came to US. Now my current project in L1B ends by Apr 30. I would like to stamp my H1B now.

1. Is my H1B petition valid till now?
2. Can I apply for a COS on my H1B and get apporved before Apr 30, and continue my stay in US?
3. Can I go to Mexico or Canada and get it stamped?
4. Can I go to India and get it stamped? Or should I apply for a new H1B this year?