They may need more information or feel that something was not disclosed, Contact an immigration attorney prior to your 2nd interview.

How can I help them? Or what are the possibilities that they will be able to get their residency through me?

They may have options? Did they enter the country on a visa? Have they every left the US and reentered? Has their been a I130 filed for them prior...

I765 EAD& i485 Adjustment of status

You usually get the EAD after 90 days. Getting the EAD is not a guarantee the I485 will be approved.

How long does it take that children of permanent resident become citizen of USA?

Your mother can apply for her unmarried children under 21. It can some years. Once they get their GC, they would be eligible to file for...

How to stay n work in USA legally with my prosperous internet startup and i'm running out of time?

Set up a consultation with a qualified employment immigration attorney.

Is there any issue in staying in US with out H1b extension ??

If the status has expired and there is no extension, you do not have lawful status. Talk to the company's immigration attorney.

Waiting for interview date

It can take more than a month for the interview to be set up. It depends on the availability at the consulate also and also NVC has to process the...

Why are they taking long time to give me an interview date?

Please talk to a qualified immigration attorney to clarify your confusion here. GC holders do not need a visa to enter.

Will this be an issue during my visa stamping? Will they reject my visa for all these?

Have your company's immigration atty review your certified disposition (what happened with the du1 and prior incident with your gf) and advise you...

Does traveling cause any delay of my I-485?

A short trip outside with a valid AP should be fine but you need to be present for the biometrics and interview. Also unless really necessary wait...