L1B to H1B conversion through Consular Processing

[smartap]

Hello Friends,

Currently i am working in USA for ABC company on L1B which will expires in July 2019.

An employer XYZ filed H1B through consular processing for me and waiting for approval at he end od the month Jan 2018 or in Feb 2018.

My current employer ABC is asking me to stay in USA till Sep 2018 on the L1B.


Here are my questions.

1. If i will get my H1B Approval in Jan or Feb 2018 for XYZ company... Can i continue to work for my current employer ABC till Sep 2018?

2. As my H1B is processed through Consular Processing... After Sep 2018 can i go to my home country and get my H1B visa got stamped and return to USA and can start working on my H!B?

3. For the Consular Processed H1B petitions... When will be the H1B status will become active?
Is it after H1B Visa approval date?
Is it after H1B Visa stamping date at my home country?

4. For COS... The 3 years of H1B validity starts from approval date of that petition.
But for Consular Processing ... H1B Visa validity starts from Approval date onwards? or After stamping the H1B Visa at home country... from that date onwards the H1B validity start?

Could anyone please clarify my doubts.

Thanks In Advance.