In the DS-260, should i enter the building address (no flat assigned yet) in the residence and my friends us address in mailing?

I agree with both colleagues. You have a vested interest in the green card actually reaching you and not returning as undelivered. There is no...

Is USCIS give a standart 6 months of B-2 extension, even if the application was filed for only 3 months?

It could go both ways. USCIS could grant the request of the applicant for the time indicated in the request or USCIS could grant until the date on...

ADJUSTMENT OF STATUS?

You could seek adjustment of status but as my colleague pointed out, you could have a preconceived intent issue and should talk to an immigration...

It is unclear what sponsorship you are talking about. In what way are you asked to sponsor the person?

Can an undocumented immigrant, who owns a solid business, be granted with a green card filling a petition for themselves?

You could look into EB5 category for immigrating to the USA via investment and pilot program specifically. The problem would be not just getting...

Is it possible to revoke my ex-spouse green card ?

You can write a letter to immigration fraud unit if you think your spouse committed fraud, That concludes your set of options.

Do I need a separate petition?

Immediate relative is a immigrant category that tolerates no derivatives. As a result you need to file an I -130 immigrant petition for each...

Can my son apply for green card with his expiring passport?

Your needs to have a valid passport to seek an immigrant visa or non-immigrant visa at the US consulate.

Can I cross the border to Mexico from San Diego and come back ?

You can travel to Mexico and Canada on your green card alone.

How a green card holder can apply to B1 visa to a family member?

Same answer. It is not very likely that your invitation would help that much.