Welcome to disABILITIES
In answer to your first question, with ability to walk she should be able to get on all rides and attractions. If the cast is visible, and you feel extra loading time is needed she may want to go to the disabled access area.
As far as a wheelchair, the answer is a strong (sort-of) YES! Generally people walking around WDW get 8 - 10 miles per day. In a cast this will be very difficult.
A lot depends on her age and size.
If she is a child she can use a stroller and you can get a Guest Assistance Card (GAC) which will allow the stroller to be used as a wheelchair in lines.
If an adult you need to be aware there
are hills at WDW, just not noticeable to most people but definitely noticeable in a chair.
There are three sources of wheelchairs, rentals at the parks ow Downtown Disney, rental from off-site, or loan from your Disney hotel. There are two sources for electric convenience vehicles (
ECVs){sometimes called scooters), at the parks and from off-site.
It is possible to borrow a wc from your hotel for the length of stay with no fee. However, there is no promise at all as to either size, quality or availability.
Renting in the parks (wc or
ECV) or Downtown Disney (wc only) there is a daily fee plus a refundable deposit. If you rent at one location and then go to another the same day, by showing your same-day receipt you do not have to pay another daily fee, only the refundable deposit.
Renting from off-site will save money over daily rentals (espicially if a week or longer), give a chair that will fit properly, and be available at all times.
Generally an ECV has advantages over a wc in that it gives the user more freedom than a wc, but of course it costs more (about $30 per day compared to about $8 per day).
If you can give more detail, we would probably be able to answer the question better.