I had a TKR and needed a Hip replacement as well so I have been ordering scooters at Disney for about 1 year and a half. I have always used a company that can drop them off without you there. I've used Big Apple and Scooter Bug. I only once had an
ECV that didn't last the day. Then I realized what the "box" was at the bottom of the scooter, they had given me a 2nd battery pack! You can leave it nearly anyplace where you see strollers lined up. If you can find a plug, plug yours in to charge. Even a half hour helps.
They will walk you through using it if you don't use Scooter Bug. The tiller turns it left or right. It's adjustable back and forth. The seat has a lever and you can turn your seat to the right or left a quarter turn at a time. There is a key that comes out and turns it on and off. Take it with you when you leave it. There's a lever that controls it forward and backward. And there is a speed control next to the key. This is an important feature and needed to get on and off a bus, the monorail, a boat or the Skyliner.
Most stores have room for an ECV, especially today because of COVID-19. Watch the floor markings! If you can't get into an aisle, tell a cast member. They took down a rope for me in the candy store on Main St 2 weeks ago. Nearly all rides are ADA accessible. Ask a cast member at the entrance. I've taken an ECV through the line on Pirates, Pooh and It's a Small World to name a few. Something like Haunted Mansion or Spaceship Earth you go in through the exit. Again, ask a cast member.
The buses are great, they will keep your party together if you want. Stand with your Mom. It's OK to go around the lines at the bus stations at the parks. There are rectangles on the ground for her to park and wait for a bus. ECV's are first one's on the bus and last ones off. There's a handicapped gate. Stay behind the yellow line. Parking the EVC on a bus is easy, if you can parallel park. Pull it on the bus and make a quick right. Get the rear edge or your ECV lined up with the end of the area where it parks. Slowly (turn the knob down on the ECV) and go backwards turning the front wheel and pull in the space until you're at a 45% angle and then turn back the EVC to straight and pull in the space. The driver will ask you if you want to stay in it or transfer to a seat. I always stay in mine. The driver will then lock it down with belts and put a seat belt on the rider. Don't forget to turn off the ECV and remove the key. Do NOT let the driver take the key. I once had a driver insist she had to take the key. I told her no, it wasn't her property, she insisted, she went to get another bus driver and he told her they were not supposed to take the keys.
Getting off the bus is easy. Reverse (slowly) until you gently bump the scooter. Turn the front wheel all the way to the right. The gently go forward. You're going to think you're not going to make it. Don't worry you will. Go down the ramp and to the right and you're on your way. The Skyliner is pull it in and back it out, both on the same side. The Resort Monorail is pull it in one side and then back it off or pull ahead depending on the stop.