Hi Samuel,
I've traveled many times to WDW with my DS who has CP & I've found it to be an awesome place for kids w/ special needs. The parks rent strollers (single or double), wheelchairs & ECVs on a 1st come basis. Neither can leave the park in which they were rented. If you park hop, you can retain your receipt to show at the next park to obtain another one (if available). If you plan to rent on multiple days, a "Length of Stay" rental will save you a little $.
There is a local vendor in Orlando that rents special needs strollers
www.orlandostrollerrentals.com. They offer free delivery to Disney resorts & Disney area hotels.
Be sure to visit Guest Relations & request a Guest Assistance Card for your son which will alert CMs at each attraction he requires special assistance. The GAC will allow him & up to 5 other members of your party access to alternate queues where available. If you decide to rent or bring a stroller for your son also request a band to go on the stroller & a stamp on the GAC indicating that he is uses it as a w/c so he will be able to use it at attractions - otherwise you will be required to park it in designated stroller parking areas.
WDW is a great place for people w/ limited mobility to visit & they have tried to make the parks as accessible as possible for everyone. There is a section on the WDW website devoted to
Guests with Limited Mobility. Under that section, you'll find a lot of helpful info regarding navigating the parks with special needs.
Please let me know if you have further questions. I am happy to help you make this a stress free trip for your family & son. Wishing you many magical memories :-) Allison