You will need to transfer from ECV to wheelchair for some, but not all of the lines. Don't think you can walk the lines! Know how many steps you can take (they ask) and then subtract about 5 from your max ("steps" are relative and you will get tired as the trip goes on, adjust accordingly). Boat rides were a really tough in/out, as was space mountain (they seat you in the front seat of the car because there's more leg room but if they don't, ask for that seat, it's easier. Boats are a little easier if you have someone to lean on to get in and someone strong enough to help pull you out. Spaceship earth had a weird accessible entrance - you had to walk up kind of a steep slope. Any omnimover has the ability to slow or stop the moving walkway. Slowing it worked for me. As someone else said, avoid water rides. ToT ask for first row if they don't seat you there to avoid steps in the ride vehicle. After space mountain, I chose not to ride Big Thunder because I didn't want that much jostling to cause any extra pain so just FYI to choose your rougher rides carefully or avoid depending on your pain level. I didn't even want to try Autopia (not a fan of that ride anyway). I think I managed everything else ok - that's all I can remember. I also tried to think through what I would be ok trying to evac from, if it became necessary.
I recommend having a plan for eating. For most places, you won't be able to take the ECV inside. If it's quick service, you can do an outside table if the weather is ok. For ADRs, make sure to tell them you have an ECV and can't walk far and therefore need a table close to the door (I had family members do my plate at the buffet). Note that near door may end up being far from bathroom. We were a party of 9 and had both my ECV and another family member in a wheelchair so we tried to eat at off-hours to increase our chances of finding a table that worked for us. All the table restaurants worked with us to be accommodating.
Also, fwiw, my doctor advised that I wear the boot at all times, especially in the parks because it better protects your leg when you're getting jostled on rides and because, with all those people, you can't account for who may inadvertently bump into you/it or, worse, run into you with a stoller/wheelchair/another ECV. I did that and saved the brace for the hotel room.
My other advice is make sure you have a plan for icing the ankle each night. Have a great trip!