I'm glad DD is asking the questions, and has her answers. It's even hard for an adult to understand MS and the impact it can have on one's life, unless they live with the disease. Even then, I don't know how another with MS can be, even though I can form a general idea.
Please be sure she understands too that everyone's so very, very unique, and not all you see will be in a wheelchair. My first 'exposure' to folks with MS, well into my 20's, was solely seeing those in wheelchairs, so I always imagined MS to be the 'chair disease', until I met my coworker who suffers cognitive and vision disturbances, but walks without aid.
When I was diagnosed, had I not known the cognitive/vision patient, I'd have thought my future would be in a chair. Heck, it could still be, but the % chance is slimmer when you consider the number of those diagnosed and not in chairs.
So stress that MS is like everyone's snow flakes, and we're all different.