Post #2 of the disABILITIES FAQs is the one for mobility/stamina and has the information you will need.
The lines for almost all attractions at WDW are "mainstreamed". This means that the queue is set up to allow wheelchairs and/or
ECVs to go through the line just as a person without a mobility problem. As it was built prior to the ADA, the Magic Kingdom is most likely to have non-mainstreamed lines. Some attractions, such as Splash Mountain and Haunted Mansion you will go part way through the regular queue and then be diverted. Other attractions, such as Big Thunder Mountain or SpaceShip Earth you will initially be directed to an accessible entrance.
All the theaters are set up with seats (usually in the back row) removed so a wheelchair or
ECV can pull into a space and there will be regular seating on either side of the space for the others in the party.
Where there are quantity limits on space, or other limitation involving accessibility, you may have to wait longer to see a show or ride an attraction than people without disabilities.
The normal (and official) response of Guest Relations to people with mobility and/or stamina issues is to recommend rental of a wheelchair or ECV. The Guest Assistance Card (GAC) is intended for "invisible" disabilities not related to mobility or stamina. A wheelchair or ECV is sufficient to notify Cast Members of special assistance normally needed.
Please ask your husband the following questions. Here are the suggested answers to go with them.
1. Are you disabled (even temporarily)? Yes.
2. Do the people you are traveling with, such as your family, know you are disabled? Yes.
3. Do you expect to meet anyone you know during this trip who may not know you are disabled. Probably No!
4. Do you expect to meet a bunch of people who you will probably never meet again in your life? Probably yes!
5. Is there any reason at all that you should care what these people think about you? Absolutely No!!
6. Will using a wheelchair or ECV make for a better vacation for you
and your family? Absolutely YES!