Here is some additional fastpass+ related info. This comes from Disney's Terms and Conditions, but as always this can change before launch.
Web Site / Mobile App Features:
Disney will add a "Friends and Family" feature to the application and website. Through this site you will be able to create a profile for you and members of your party. You will also be able to add other friends by either sending an invite using their name and birthdate or connecting though friends of friends. You must be 18 or older to manage the account, but there can be managed accounts for children 13-17 that have limited functionality. Children 12 and under are not permitted to register, but can be managed by an adult. There will be two groups of friends, "Managed Friends" and "Connnected Friends". Managed Friends are profiles that the main user creates and manages on thier behalf.
Once friends are accepted they can share information and plan activities together. Friends can share character photos and make plans for both their managed and connected friends. There will be a choice to share all activities with connected friends or just the activites that you have in common. Friends will be able to arrange dining and event reservations together.
The number of Fastpass+ experiences you may select and arrival windows are limited and based on factors such as the theme park you are visiting, the attraction type, the time of year, the day of week, and the prior demand for the expierience.
You may make Fastpass+ reservations for yourself, your managed friends, and your connected friends. Reservations made on behalf of friends will count toward their allotment. Your connected friends may also make reservations on your behalf.
You can only make Fastpass+ reservations for one park per day.
You can only book the same Fastpass+ expierience once per day per person.
If your plans change you can cancel your Fastpass+ reservations for the entire day up until the first pass is redeemed or the first usage window expires.
Unused and expired Fastpass+ reservations are not refunded and count toward your allowance.
Magic your Way ticket holders may make Fastpass+ selections beginning 60 days prior to the day of use. The selection window may vary for other tickets or passholders. Passes with blackout dates won't be able to make Fastpass+ reservations during blackout days.
Fastpass+ will be avaialble for some dining expieriences. This will secure an arrival window and allow you to order before you arrive. This could apply to both quick service and table service.
Edited for spelling.