Pickup from Park?

It has been our lucky week...I am a high school teacher, and have been asked to chaperone our choir field trip to Orlando next week (another teacher had to withdraw)!!!! My school is amazing enough to allow my five-year-old to come along. He's a Disney pro, but I want a "Plan B" if the high schoolers' schedule is too much for him. Can anyone give me advice about how to work with a ride system like Uber at WDW? Or to use a taxi? Is there a specific spot that we would be picked up (or want to get to to be picked up)?

Thanks so much!

Can you leave the group if your son is tired or wants to leave?!?
Cabs are available at every park or resort entrance.

Yes, we can absolutely leave. So I would just go with him to Guest Relations?

For AKL, DHS, and Epcot just exit the park and go to the cab stand. For MK you could either go to the TTC or walk over to the Contemporary and grab a cab there. I suggest you check the fares out before hand so you have an idea what the cost should be and always ask the driver before getting in the cab, I had one in Epcot that tried to scam me....didn't take the ride and reported him to Mears.