Why did I get another biometric notice for I-751when I had one done already ?

Unclear why you may need another biometric if it was already completed but best to attend this appointment as previous biometrics may not have been...

Due to some unforeseen reasons I have not attended the biometric for my green card processing.

Yes departing will result in the abandonment of the file. A subsequent filing for visitor visa may be difficult but you can apply for an immigrant...

CSPA applies to siblings when petitioning a parent?

No as there is no derivative beneficiary for this category of filing.

No the expedite request should not delay the normal processing of your case.

My husband already went to the interviewin cuidadjuarez ?

Yes it is likely he will he called for a second interview after the waiver approval.

Form N400. My father is a citizen but i fill on N400 none citizen. Now waiting for interview

You can inform the officer at the time of interview without issue.

Inquiry

No the spouse must be a USC to apply for a spouse that has overstayed.

Contact USCIS and inform them of the missed appointment and request for a rescheduling right away.

Is there is a new law made for the U.S citizenship?

Yes all co-signers must complete the I864 and provide the necessary documents.

Can I marry while my asylum is pending and I am in court? Will it affect me?

More information is needed about your fiancés status but yes, otherwise you can marry while your case is pending.