Walt Disney World Resort can be a pretty good grind, and you need to expect to every bit of 10,000 steps. If you're not up to that, it shouldn't diminish your ability to visit the Resort with family and friends. We have used a service (Walker Mobility) for our clients for years, and this past visit got to use them first hand.
You need to tell your Travel Professional that you're going to need that, and also that your room is available to accommodate a scooter. (Side note: even then, you might have to do a little work with the front desk. They missed it on our reservation at Old Key West and had us in a 2nd floor unit without an elevator. Easy fix, but one that you'll have to anticipate depending on your situation).
All Disney motorcoaches are equipped with ramps, and strap the scooter and occupant in. There's only two per coach, so there might be times during peak periods where they have to either come back or radio ahead to send a coach for you. There is a spot at each Coach stop for handicap guests. Important that you're in that spot so the driver can see that he needs to accommodate a special needs guest.
Each driver is different. Some will operate the scooter to park it, some will want you to do it, some will do a combination of both.
At the restaurants, they will ask if you want to stay in your chair or transfer to a chair of theirs.
At the parks, there are a variety of options depending on the attraction. The mobile app will let you know whether you have to transfer to a wheelchair, accommodate your scooter (like the Jungle Safari pictured below), or not available to accommodate you.