L2 to H1, L2 visa expiring soon, COS pending approval

[goldengate]

Hi All,

I have an approved H1B petition(filed and approved while in India) from employer A. But I did not go for visa stamping, as my employer scrapped the project.

I got a L2 visa and traveled along with my spouse to US.

Now, employer B has filed I-129 using H1B portability option (using my approved petition from employer A).

Application I-129 is pending for approval, whereas my L2 visa is going to expire in a month.

1. Can I start working with the petition number of the new I-129 (employer B), as I already have a valid approved petition (from employer A).

2. Will I be able to stay legally in US, while my I-129 is pending for approval, after my L2 visa expires.

3. In the worst case, if my I-129 gets rejected, will I have a grace period of 1 month to leave US, or should I leave immediately? In that case, will my stay after L2 expiry be considered illegal?

Thanks in Advance.