We are at WDW now. We have our green Annual Passes and Magic Bands, and were given resort room key cards at check-in. The cast member checking us in told us we may need the keys for some restauants that couldn't use the Magic Bands yet.
We have barely needed fastpasses but have found that we can get paper fastpasses using our AP's and our room keys as mentioned by others on earlier visits. The fastpass eligibility times are not linked between the AP's and room keys so we could get muliple FP's at the same ride or get a FP at one attraction and immediatly use the other card for FP's at another.
I have changed FP+ during the day and have also switched over to a different park after we decided we didn't need FP+ for the park we were in during the morning. I was able to switch over to a different park after the FP+ time had expired on one of our FP+'s but we hadn't actually used any FP+'s yet. On a day when we had used one FP+, we were not able to switch the others over to another park for use later that day.
We have barely needed fastpasses but have found that we can get paper fastpasses using our AP's and our room keys as mentioned by others on earlier visits. The fastpass eligibility times are not linked between the AP's and room keys so we could get muliple FP's at the same ride or get a FP at one attraction and immediatly use the other card for FP's at another.

I have changed FP+ during the day and have also switched over to a different park after we decided we didn't need FP+ for the park we were in during the morning. I was able to switch over to a different park after the FP+ time had expired on one of our FP+'s but we hadn't actually used any FP+'s yet. On a day when we had used one FP+, we were not able to switch the others over to another park for use later that day.