Can i get Green card on my situation and will get it approved after overstay?

Visa is automatically cancelled if you stay past I-94 and extension is denied.

Can I transfer my approved H1B COS to L1 COS again with the help of an attorney personally ?

I don't see any other option except that you will have to depart the U.S. if you do not wish to join your H-1B employer. COS is not possible as...

Can my mother apply for Green Card now? What are the possibilities of granting Green card?

If she collected unlawful presence of 6 months and over, they will be subject to bars. It is best to have her file reviewed by an immigration...

Can i apply for visitor visa extension second time?

B-2 extension for child care will not be approved.

I forgot to mention paid traning programme(Internship) of 18 months on n-400?

Before the IO gets to it at the interview, be upfront and seek to amend your application to include this information.

Can I transfer H1 B to a new employer with pending amendment through current employer ?

Yes, if the I-94 is still valid

It does not hurt to bring it along to the interview.

I seek for H1B job. My potential H1B job is not related to my study on F1 visa. Is it legal?

Yes, job search in F-1 status is not an illegal activity.

Regarding my H1B COS issue

If there was a problem with the filing and/ or your status, the company attorney would advise the company. If you do not get your query answered...

Entering US with few days of stamped H4 Visa left, but extension approved

No