Number 2 - I would answer maybe, depending on how much I think I would save.
First time using NCL air:
We flew in the day of the cruise, we were delayed but we made it on the ship. We knew the risk, they booked us on the correct flights and everything worked as expected. We had some delays but we made it, we were flying from Pennsylvania to Miami so flights are pretty straight forward.
I am currently using them a 2nd time, I am not sure I would use them again after this experience. We received the flight info early, I think it was around 65 days before the cruise. However they had us flying out of Chicago instead of Harrisburg PA. Simple mistake, no big deal, called them and they said they would fix it in 14 days. Long story short it wasn't fixed in 14 days, it took over 6 weeks and was finally fixed 17 days before we leave. We kept getting the run around and said it might not be fixed until 3 days before we leave. I finally raised it as a big issue, threatened to file a complaint, etc and two hours later it was fixed. Also they didn't pick the best flights but at least we have flights.
If everything goes smooth then it is worth the savings, but if something goes wrong they are not the easiest to work with. Not sure the hassle is worth the savings, so depends on how much we save and how complicated the flights are.