It appears your I485 may be denied for untimely submission of I864.

Yes, that would be a problem. Resolve ASAP.

Petitioner may be given the opportunity to explain the contradiction via RFE before decision.

Answer "Yes" Explanation in your own words. "...because I just didn't work..." Good luck to you.

Your employer's lawyer has all your information to appropriately counsel you. Good luck.

You may complete I751 with changed name. Attach court divorce order.

No issue here, as a family member can help applicant in completing N400.

As written, you don't have an immigration question now. I have transferred your question.

As a German you may retain US citizenship.

I agree with the above observations. Your contemplated action would slow down your waiver.