Please consult with an immigration attorney.

So long you are maintaining your F1 then spouse can get F2

Consult with an immigration attorney. Depending on when would you become US citizen, for now may apply for only I-130

Expire passport is not an issue so long you have ID to get in to the building for the interview and you have your green card with you.

Due to COVID-19 the Immgration is short staffed and also December has lots of holidays. Your submission is recent. For now Just wait a bit more.

You can attach a sworn statement/ affidavit that you didn’t get the notice. But also look at the N-336 time-frame. May be refiling N-400 is more...

The beneficiary’s criminal record matters not the US citizen- you can petition.

Best path forward would be I-485, once fiancé becomes US citizen.

It is very much discretionary. Beside filing fee there us no harm in filing it. Good luck

If you manage to get medical done before filing then try to send it with the package. Because if you don’t submit now then you may get an RFE that...