Yes you may submit updated I864 at time of interview.

No do not wait and obtain a cosignor for this purpose.

No unfortunately you may not sponsor yourself.

It was done by USCIS error and is nothing to be worried about.

This will not impact your application for your spouse.

No the I485 is pending and will suffice.

You may use form I864 for affidavit of support purposes.

Contact NVC to request reinstatement of case based on your particular circumstances.

The NOID will be denied for abandonment if not responded to. However with a pending AOS, it is not necessary.

Your GC would remain valid despite divorce.