I think I can help and answer some of your questions.
I'm one of those people who has always redeemed my Airmiles for Disney tickets, the last time being in Feb (4 months ago). I usually recommend redeeming for the cheapest ticket available to save on points, then upgrade at the park after using the ticket at least once.
With FP+ and pre-booking, I have somewhat changed my strategy. I now redeem for the 5 day ticket (extra 75 pts for a 25$-ish value). I really don't want to use 200 extra points to go from 3-day to 7-day (only a 45$ value), but I'd consider it if I had to.
You will receive a real RFD enabled ticket, generic, no name on it.
You can link it to your
MDE account. Once you have it linked, and you have a resort stay, it will 'unlock' your ability to book the number of days you have tickets for.
For example, if you have a 7 night on-site stay, and a 3-day ticket, it will let you book any 3 days' worth of FP+ that fall within your hotel reservation. They do not have to be consecutive days.
(edited to add that I have no idea how off-site stays work now that they can pre-book FP+, but I am assuming that they can book 30-days out up to the number of days that they have on the ticket linked in MDE).
So my current strategy is to redeem for the 5-day pass (the extra 75 pts is acceptable to me), even if I'm staying longer. I will not book FP+ on days that I am going to AK because they're really not necessary, or on my days off. I will then use my pass to enter at least once, and then upgrade to add extra days or PH when I get there.