No unfortunately the child of the parent cannot be included.

Very sorry to hear this. You have limited options given yours and his status. Consult with an attorney for guidance.

Yes you must be married and reside with spouse for 3 year rule.

Write a letter and upload it online.

No not if filing with pending I485.

A certified copy should be sufficient.

I agree with my colleague re: gap in authorization.

That is not needed for interview but the marriage may be addressed.

Best to consult with an attorney for review of your case. Good luck.

Keep checking but likely not any faster than current.