Since you booked a package through Disney, there are a few smaller "perks" - I think it's mentioned in your reservation paperwork but will be included in your folio when you check-in. It may change, but usually there is a discount on mini-golf, possibly discounts at a couple of DTD restaurants (I'm thinking I recall Planet Hollywood and House of Blues in the past), discounts on some recreation opportunties (boat rentals or jet skis, etc.). You mention character calls, and while I've never done one I believe you can request a wake-up call in your room and it will be Mickey. You can also make ADRs at 180+10, which means that at the 180 mark from your check-in day you can make up to 10 days worth of dining reservations; people staying off-site must call at the 180 mark for each day.
If you think there are other benefits you had read or heard about, feel free to ask about something specific (like you mentioned character calls).
Enjoy your vacation! I think you'll enjoy staying onsite!