Yes...you can use your AAA card for discounts at stores and restaurants at the parks and some places at CityWalk. I don't believe they automatically put tips onto your bill...that's never happened with my AP.
We've been here for 2 1/2 days, and I've saved about $20-ish dollars on drinks, food, souvenirs...Most places do take it. Some of the kiosks drink vendors do...and some don't. The Minions gift shop definitely takes it...and takes.. It...