You don't have to have Magic Bands for FP+ to work, but can buy them for I think $15/each. You need to sign up for My Disney Experience and then 30 days from each day of your stay, log on to your account and choose your 3 FP+.
We are staying off site and ordered out tickets through Disney. When they arrived, I logged into My Disney Experience acct and linked the tickets with the acct and each person going. For FP+ not everyone in your party has to get the same FP+. Our tickets then are our FP to get on these rides.
Hope this helps! Getting excited, we arrive 4 weeks from today. Started making out FP+ choices Saturday night and have 2 days down and 4 to go.