L1B to H1B , H1B approved and Applied for L1B extension

I am working for employer1 on L1-B. my visa & I-94 is going to expire by Feb 6 2014.

I have applied for H1B through employer2 in Apr 1 2013 as a COS from L1. 
My H1B petition went to RFE->Denial->MTR->Approved status and I got the petition approved on Jan-21-2014. I am waiting for approved petition.

My employer2 told that once I get a client project, I will start working for employer2 after serving 2 weeks notice to employer1.

In the mean time, my employer1 has filed L1-B Extension on Jan-23-2014.

1. Without any issues when I should convert my status to H1B when my L1-B extension is in process
    1.1 Before my current visa expires on Feb 6 2014?
    1.2 After my current visa expires on Feb 6 2014?

2. Do I need to go for H1-B stamping to my home country in order to start working in H1B Since I have filed L1-B extension?

3. What happened to my H1B petition if my L1-B petition got 
    3.1 Approved or 
    3.2 RFE or
    3.3 Rejected

4. When I need to ask my employer1 to withdraw L1-B petition. 
    4.1 Immediately or 
    4.2 Shall I wait till I get a project thru employer2 and start working for them?

5. How many days I can legally work for employer1 in L1B before I start working for employer2 in H1B as my H1B got approved and waiting for the approved petition?

Please advise.