H1B transfer to different employer

Im currently on L1 Visa in US with Employer A , also filed for H1b with Employer B.
H1B was filed while im in US.

I would like to continue on L1 until its valid. Once my L1 is expired would like to transfer to H1B. is this possible or do i need to transfer as and when my H1B is approved??

Also can i transfer my H1B to a new employer(other than employer B) while im in India??

Anyone said to be in a STATUS while they are legally living in US.
While on a STATUS(for your case, its L1), you have applied to change to another status(by your Employer B). Once this Employer B H1 petition approved, you are legally on H1 status and no longer on L status.
You cant request a status for a per-determined date.
BTW, there is nothing called transfer of a status.
Also, YOU cant do anything to your H/L visas, your employer only can do.

To add, just check with your attorney, if they filed it as Change of Status (COS) or Consular processing. If COS, then you are automatically changed to different status. If not, you can do COS later anytime you want.