You can have as many Magic Bands as Disney will send you (which, for now, will be for every single resort reservation you make). We will be getting 3 bands, per person, for our Feb/Mar trip, since we'll be staying at 3 Disney resorts.
When you get them, link them to your My Disney Experience account, using the serial numbers on the bands. Then, they'll be interchangeable. For example, if you order a Blue and a Pink one for yourself, and you link them both to your MDE account, you can alternate which one you wear because they'll both work.
As for the AP question - I'm not entirely sure. I suggest you go ahead and link your current APs to your MDE account. Then, when the 60-day FP+ window opens, see if it will let you book FPs. If so, you should be good. If not, you'd want to get your renewal vouchers ASAP and link them to your account (I think that's possible now).