As I recall, my wife's NC came back as 1st class mail....USPS.....not Priority mail...so no carrier insurance at all..In addition, $100 only covers about 1/5 of the cost of a new NC. I would go straight to DOS.
You should enter any information you know (such as parent's name)....and you can enter "unknown" for information you do not know. "N/A" would not be appropriate in this case.
I would just use a copy of the 2 year card. You can explain at the interview, if asked. Plenty of people (such as my wife) used a copy of their 2 year card for the N-400 since our I-751 was still pending. The 2 year card (residence since" date) will establish when the Green Card holder became a legal resident.
I think you will receive good news soon. Keep an eye on the USCIS status. Remember to collect evidence for your I-751 through the next 2 years. Collecting pieces of evidence of a bona fide marriage along the way will make the removal of conditions paperwork a lot easier. Good luck on the rest of your journey.
USCIS says about 8 months for Dallas. I think it said 9 months when my wife applied in late 2022. It actually took only 3 months to get notification of an interview. Total time (over the holidays) was 5.5 months from application to oath (and that included a combo interview).
if illegally present. They aren't picking up people who have authorized stay, to my knowledge.
Illegally present means deportable. Tom Homan has said they will pick up people illegally present.