You will need a wheelchair full time, so renting one at the parks or getting one first come first served at the resort will not do the trick. In order to elevate her foot, you will need a wheelchair with elevating footrests. I know most of the park rental one I have seen have swing away footrests, not elevating ones. You will be able to get an elevating footrest one from any of the offsite rental places.
An
ecv would be nice for getting around, but there is no arrangement that I know of for elevating either foot. They have sort of a flat "floor" for you to place your foot on.
My DD's manual wheelchair has been on all the rides where you can stay in the wheelchair. Some of them don't have a lot of room in front and I'm not sure they would accomidate a wheelchair with the footrest elevated. Here is some information I copied from the official Disney Website about rides that have extra room and could accomodate someone in a full leg cast. I know she doesn't have one, but the extra room info is the important part:
Magic Kingdom
Walt Disney World Railroad **
The Jungle Cruise (may be hard to get on)
Liberty Belle Riverboat **
"it's a small world" **
Cinderella's Golden Carrousel
The ExtraTERRORestrial Alien Encounter **
The Timekeeper ** (not sure it's open)
Walt Disney's Carousel of Progress **
"The Enchanted Tiki Room Under New Management" **
Country Bear Jamboree **
The Diamond Horseshoe Revue **
The Hall of Presidents **
Legend of the Lion King **
Epcot
Ellen's Energy Adventure (Universe of Energy) **
Cranium Command (Wonders of Life) **
The Making of Me (Wonders of Life) **
El Rio del Tiempo (Mexico) **
Wonders of China **
The American Adventure **
America Gardens Theater **
Impressions de France **
O Canada! **
Honey I Shrunk the Audience **
The Living Seas **
Living with the Land (The Land) **
Food Rocks (The Land) **
Disney-MGM Studios
The Hunchback of Notre Dame **
Muppet*Vision 4D **
Indiana Jones Epic Stunt Spectacular **
Sounds Dangerous **
Disney's Doug Live **
Backlot Tour **
Backstage Pass Walking Tour **
Voyage of the Little Mermaid **
Bear in the Big Blue House, Live on Stage **
The Magic of Disney Animation **
The Great Movie Ride **
Beauty and the Beast, Live on Stage **
Fantasmic! **
Disney's Animal Kingdom Theme Park
Pangani Forest Exploration Trail **
Wildlife Express to Conservation Station **
Conservation Station **
It's Tough to be a Bug **
Safari Village Trails **
Festival of the Lion King **
Pocahontas and Her Forest Friends **
Maharajah Jungle Trek **
Flights of Wonder **
Tarzan Rocks! **
I deleted the rides that I know would jostle her (like Star Tours) and I included the other parks in case you decide to visit them. I marked a double star ** for the attractions where she could stay in a wheelchair. I think all those rides would accomidate an elevated footrest. Your party will be able to board together; usually they say a party of up to five plus the guest in the wheelchair can stay together. in most cases, you will be waiting in the regualr line anyway.