L1 and new H1B - 2020

I am currently on L1A visa with company A and I have been picked up in the H1 B lottery for 2021 by another US company B. Questions are below.

  1. If I get my H1B approved should I join the company B immediately? Would my visa status change to H1B status automatically once the H1B petition is approved? Or I can decide when to join the new company B and change the status from L1 to H1B later?

  2. while my new H1B petition with company B is under process , can I apply for my current L1-A extension? Would it have any impact on my L1 ?

  3. If I don’t proceed with my H1B petition after the lottery approval, would there be any impact on my L1 extension?

please help to clarify