Hello! Have you been to the disabilities forum here on the Dis? They have a lot of information about wheelchairs and accessibility. I have been to DL in a wheelchair myself and have gone with children in wheelchairs. Do you think you will be bringing your own or renting while you are here? It is recommended that you rent from an outside company to ensure availability and also for use in getting to and from the hotel (if within walking distance).
California Adventure has mainstreamed lines, but at DL things are a little different. At DL, several of the lines are not mainstreamed and you enter from the exit or another alternative method. When you arrive, stop at City Hall and grab a disability guide. It gives clear instructions on which rides you must transfer and where to board. If your daughter has other needs besides those related to mobility, City Hall would be where you request a Guest Assistance Card for those needs. Otherwise, the wheelchair is all you need.
Some lines can have longer waits for the disabled. For example, Pirates can often have a longer queue for disabled access than the regular line. Space is another one where the handicapped line builds very quickly. So your touring plans should take that into account. When I was in a wheelchair for a short time, I went on Space multiple times first thing and then Pirates and then It's a Small World. In DCA it was easier to get FP for everything, since the FP line was fully accessible.
Let me know if you have other questions. I hope your daughter recovers quickly.