Spouse? Just confirming you have a fiancee and not a spouse.
Both are irrelevant for K1s.
They are only relevant for spousals so please confirm above.
(Presuming you checked current K1 timelines in your country only).
Wait for instructions from Embassy. The last question on the DS160 eludes to having received instructions before filling out.
NOA2 is valid for one year in 3 four month increments. It automatically extends without doing anything.
She does not have to have an interview by the one year validity date either. She just must be SCHEDULED for one before the one year is up. The interview can TAKE PLACE AFTER the one year as long as it was SCHEDULED BEFORE the one year validity date.