To maintain L1 /L2 status, is it necessary to stay the person in US?

Ifi the visa is unexpired, and multiple entry, you can return on the L1/L2.

I am green card holder and my husband put my petition file and my status was F2A and my husband is still green card holder

Five years.

I-130.

Can I or my kids apply for a green card?

They need to be 21.

What public benefit can someone obtain if they are petitioning to bring in brothers and sister (family 4th preference)?

If you are minor children and your mother is supposed to be supporting you but is not, then it may affect your aunts' and uncles ability to prove...

Is my husband, a lawful permanent resident (under 5 years), at risk for being removed from the U.S. with a Class A misdemeanor?

Domestic violence is its own ground of removal, so check the definition of the offense and determine if it is also a crime of violence. If not, he...

Any type of envelope is fine, and you can send by US Postal Service or any private courier.

If H1-B gets denied, can a same employer file a fresh H1-B petition for the same person and for the same position?

Yes, this is an option, assuming there are still H1b's available.

I-485

You should start all over. Had you hired an attorney, the attorney may have notified you of the consequences of failure to respond to a request...

H1B, lost job, now new offer 10 months later to go back

You are not exempt from the cap, you can have a petition filed April 1, 2013.