We just got back last week and used the magic bands at pop century. Ours did ship to our home before we travelled, although there was a huge stack of them on check-in at pop for other guests. When we customized ours, they shipped within a day!
As for fast pass plus, I would take advantage of it. We are not over planners by any means, but it was really nice to grab some of the bigger ticket items ahead of time. Especially when we knew we'd be hitting a park in the evening. When we went to HS, we already had FPP for toy story, RnRC, and then fantasmic (gave us seats in the Pocahontas section...we got there at 7:45!) We also loved having it for meeting characters...so nice to walk right in and avoid a 30 minute wait! Made for a much happier child

On another day, what we'd selected just didn't fit. We were able to make changes the day of and have it fit what we wanted to do.
It really is convenient! Plus, as of now you can sort of cheat the system and use the old system, but they don't want you to and we even had a cast member ask us not to! So don't rely on that.