Generally 120 days post interview but could take longer.

To corroborate evidence already in file.

Yes this scheduling is possible before marriage.

Yes a widow may remarry after obtaining GC.

This is not a legal question. Best to discuss with some mentor or therapist.

Yes this is possible if inspected upon initial entry.

Contact USCIS directly to inquire about processing and possible expedite.

Yes an expedite request is possible given information provided.

CBP should have the I94 if the travel history is available.

Check processing times as it can be between 18-24 months.