Peter Pan and Tomorrowland Transit Authority cannot stop or slow their moving walkways. If you can manage to load/unload quickly enough from PP, you can ride. TTA has a moving walkway on a conveyor to get up to boarding so probably won't be possible if you can't stand or weight bear at all. All other rides with moving walkways can be stopped or slowed for boarding if needed. If you do need them stopped or slowed, you should let the CM know because they won't necessarily stop or slow just because you use an
ECV. Tom Sawyer's Island and Swiss Family Robinson Tree House are the other attractions that are not at all accessible.
A few rides will require you to transfer to a manual wheelchair (there will be one at the ride) to go through the queue. I know Pirates is one of them, but can't remember the others. If there's someone with you that can push for that distance, then you'll be fine. Cast members are not allowed to assist. The chairs are probably too heavy for you to self-propel.
If you look at the Disability FAQ sticky on the top of this board, it has quite a bit of information about what attractions have special queues or boarding information. Also, when you arrive, it's worth picking up the Guide Map for Guests with Disabilities. It gives all the information on how/where to access rides with a wheelchair or ECV.
One thing that wasn't mentioned earlier, by the way, is that it's generally best to avoid renting an ECV where you're within 25-50 pounds of the weight limit (it's just worth noting in case). In your place, I'd go for a four-wheel instead of a three-wheel because you'll have better space for your foot. Charge the ECV every night. Make sure the light on the charger has turned to green before you unplug it because that light is more accurate than the meter on the tiller. You can't overcharge the battery. Both when I used an ECV and with my powerchair, I generally just plug in before I go to bed and unplug in the morning. I'd allow at least 6 hours to fully recharge. There are a few places in the parks you may be able to plug in during the day to partially charge if you're getting low, but that's really bad for the battery. We've had one person recently report they were told they could only recharge at the stroller/ecv/wheelchair rental location. I wouldn't count on recharging at the parks and really only do it in an emergency. 9.5 miles should work unless you're going rope-drop to closing and back and forth across parks. (It would probably last in some of the smaller parks regardless.) There are definitely
ECVs out there for rent that have a longer range than 9.5 miles, as well. If you check the FAQ, they have a list of rental companies that board users have had good experiences with. So far, every one from the FAQ I've checked has had a scooter with a larger range so it may be worth checking some other rental companies (I don't know who you're currently planning on renting from).
we are in the parks early morning until closing we have not had any issues with battery life for the most part. One time I forgot to charge it overnight and simply charged it in the park while we were eating. My DH and I have a great time scooting the world. 
