How does Step-Parent adoption work in the state of Nevada?

Without the father's consent, you would have to find a Court to terminate his parental rights. Not very easy.

Applying H4 when H1 is still pending

Sounds like you understand the scenario.

Can an illegal immigrant mother child support on an illegal immigrant father that has a deported status, can they be deported?

I am not sure of your question.

Can i apply a us passport or duel citizen for both girls??

Possibly, you should speak with German officials to see the effect of taking on US Citizenship.

Probably not much.

Is there any new rules came to extension F-1 visa?

still no

Is there anything you can do to stop a deportation?

Deportations can be reviewed in a Federal Court. If there was a serious error in the proceedings maybe. This is quite complicated and you need to...

New H1B Transfer while a Transfer already exists..

No, must wait to transfer after current transfer is approved.

Can a H1B holder marry a J1 holder who is out of the country on his 2 year out of country requirement and bring him back?

Yes and if the person stays out for 2 years no waiver is needed.

My sister went to US on b2 visa,she meet and fell inlove with american citizen.Can she marry him and apply for GC.

She can marry and maybe they will question. Hire a lawyer and be prepared for those types of questions at the interview.