Could you please tell me what date is the application form N-400 referring to in part 2 and point 9?

It is the 'Resident Since' date on the front of your greencard.

How to come back to USA?

Does your family 'treat' you as dead, or did they get a court order declaring you dead?

Can I revalidate my f1 out of status visa by re-entry through mexico?

You need specific guidance from your DSO ... depending on the reason for being out-of-status, and because it has been more than 5 months ... a trip...

N-400 Naturalization Oath Timing?

This is a duplicate question. All you can do is be patient and wait for the leather.

You misunderstand the 6 month rule. She has to be 'really' living in the US ... not just 'visiting' for one month out of every 6. Yes, she...

Hi! I work in an University (under H1B visa) in the US. I am from India and I would like to sponsor my fiance for a visit.

As Mr. Shusterman stated, you can't sponsor a fiance. You can fly home, get married and have her apply for an H-4 visa. Otherwise she can apply...

Can a non citizen own a house in the USA?

Yes, you can own property. But, how the deed is transferred can be an issue.

Can i apply for citizenship? d.o,b 07/23/1954 and have green cart cince 2004

Yes, you appear to qualify for the 65/15 exemption of the English test.

What is happening with my case?

Nine (9) months is not a long time to wait for an interview. Go and do the new biometrics.

Can i own various llc with a llc, and apply with this “mother” llc to a visa e2?

You need a business lawyer that will consult with an immigration lawyer. Although this may work, it seems like an unnecessary complex 'stacking'...