L1 to H1 Visa transfer Queries

[rizwmehm2]

The First L1B Visa was issued on December 2007 with an expiry date of Nov 2010 at a Mumbai consulate in India.

I first enter US on October 2008 stayed for around 2 years and went back to india on October 2010.

I got the Second current L1B Visa on November 2010 with an expiry date of October 2013 at a Mumbai consulate in India and came back to US on Dec 2010.

I have worked on L1 Visa only till now and both were applied by X company only .

A different Y company did apply my H1B Visa and was approved in 2008 with a validity date of Oct 2011. but i have never use or worked on H1B Visa on this petition.

I have the below Questions

1) One A company is ready to apply my New H1 B Visa right now . Can this past H1b help me not to fall in H1B Quota and can i start work before Oct 1st 2012?

2) Will the USCIS put a start date on the approval of H1B for company A?

3)If my status is changed as soon as it is approved from L1 to H1 can i serve a notice period in my current existing company or i will have to abide by the start date on the H1B approval?

4) Suppose If the start date is March 15th 2012 then then it is legal that i keep working on L1B visa till march 15th 2012 and serve the notice period or i will have to leave the country to maintain the status?

Immediate response will be higly appreciated. Thank you