Travel outside US while waiting to receive passport after passport renewal application

Yes, the US recognizes dual citizenship so they can do that. But they must have a US passport to renter.

How to extend H4 Dependent I94 if I797A is active till next year ?

Doesn’t the approval notice have an I -94 at the bottom?

I applied i-485 & did biometrics 2 mths ago. To bridge the visa gap I have to do I-539. Do I need to pay separate biometric fee?

If your I-485 is filed you do not need to maintain status. Further, with an application for adjustment of status pending an I-539 extension would...

IMMIGRATION QUESTION?

You only have to be in status when the adjustment of status application is filed. However, if for some reason the adjustment of status is denied,...

Simply tell them you are a permanent resident now. Most Americans have no idea how the immigration system works.

How fast can my Fiance get her EAD?

That depends on the FB-2A quota for India.

Can I apply for the US citizenship after 18 month or do I have to wait for 3 years?

Three years since you were out more than six months.

I am Undocumented But my uncle wants to adopt me then later file citizenships for me, would that be possible nor not ?

Only if you are under 16 and live with your Uncle for two years.

L2 to L1 COS pending. L2 EAD and I94 expired. Can L2 still work till COS decision?

Doesn’t your attorney know this? You cannot work without an EAD or L-1 status.

Can I (alien relative/greencard applicant) have my greencard if my petitioner/sponsor (my US citizen wife) has IRS tax debt?

Your wife must file her missing returns and also must live in the IS once the I-130 is approved.