OK, I know I'm joining in rather late on this one, but I thought I'd put my oar... I mean my two cents

in. Disney is the most accessible place I've been, so don't stress about doing this trip with the boot. I know it will mean a slightly different way of touring, and might need a slightly different mindset, but it should still be a fun and relaxing holiday for you.
When boarding rides, make sure you tell the CM at boarding what you need to be able to get onto the ride comfortably. Almost every moving walkway can be slowed down (I think Peter Pan is the only one that can't), but you often have to ask for this (they don't always offer it spontaneously, sometimes only if they see you struggling). It might take you a few rides until you find what is easiest for you. Just remember that a CM cannot give you any physical help, other than to hold a wheelchair steady for you.
Another thing that may cause you problems on rides, is those moving walkways that slope. They only have them at a couple of places, but they are very painful for me to stand on, as it forces your feet into an odd angle. The only two places I can think of with these, off the top of my head, are WEDWay People Mover (OK, so it's now called the Tomorrowland Transit Authority) and Pirates of the Caribbean at the exit; the latter of the two can be avoided by going through the door to the left, behind which you'll find an elevator. If you want to ride the TTA, you should be fine, just stand sideways on the ramp, and / or stand on your good foot (yes, it may look a little silly, but everyone will understand why you're doing it, and being at Disney wouldn't be so much fun without the silly!).
You might want to give the Swiss Family Robinson Treehouse a miss, unless you're having a very good day, or it is important enough to you to cope with the pain. It has a few hundred steps in it (I can't remember the exact number offhand), and because of the one-way system, it would be very hard to 'change your mind' part way through it. On the other hand, it does have good handrails through most, if not all, of it, which can be used to help you on the stairs. I can't think of anywhere you can sit down, on your way around, but you could tuck out of the way at various places, so you could rest without being in the way. EDIT: it's 128 steps (yes, I did just go and look that up; yes, I knew exactly where to look to find it out; yes, I am a Disney geek

)
Sorry if this has already been covered for you in another thread, but are you taking crutches? If so, you can usually get an offsite rental company to fit crutch-holders to an
ECV or wheelchair for you. It might be useful to have them with you for ride transfers, and to get around small and crowded shops, etc.
Other than that, just relax, take the time you need and have a great holiday! As HonnyDipp said, the Mouse will look after you