When your case has been pending 150 days you may apply for employment authorization. Once you receive employment authorization you should be able...

How can I get my ssn right away after getting married to a usc?

You will need to start the permanent resident process for both yourself and your son. After obtaining employment authorization or resident status...

Status check shows "Case In Line For An Interview" (N-400). After how long I would get the interview letter? in Washington DC?

You can check the local CIS office processing times on the USCIS.gov website

Good question to be directed to your employers Immigration Attorney

Is AP valid after AOS denial but before the expiration date?

Not completely clear on your fact situation. If you are saying you file for adjustment and advance parole but did not file The visa petition this...

I am a student in the US on a F1 visa and my mother who was my sponsor recently passed. What can I do?

Sorry to hear of your mothers passing. Contact your designated school official for financial aid options that may be available.

Travel to India while applying extension

Travel is permitted with a valid visa and passport. And extension filed prior to departure should be considered abandoned and thus denied.

This means USCIS has established a priority for scheduling interviews. USCIS is not bound by the priority scheduling and there may be exceptions.

Do I need to renew my visa when coming back to US mainland from Guam?

If the visa is valid you do not need to renew the visa.

Can I sponsor my unmarried 19 year old daughter ?

You will need to first obtain lawful resident status and then in turn file a petition for your daughter.