So we managed to ride the coasters Mom wanted to; thank you for the help!
My mom wasn't feeling well on her first day
and it was really hot and quite crowded and she got there late, so she only stayed a couple hours before she had to leave.
But she had a beach/alone day to recharge, and then on her other/last day, she heeded my plea to get to the parks right around park open. She enjoyed the pretty lighting conditions and better atmosphere with fewer people, but unfortunately, we belatedly discovered that Space Mountain was offline. Instead, we rode Big Thunder Mountain through the alternate exit. Eventually we got back to Space Mountain when it was just coming back online. There were 2 parties ahead of us, so we had to wait a little while, but we got to ride, first row!
SMD, I remembered your story, so I asked the people behind us if they wanted to buy their picture, since we had Photopass+ and I had suggested to my mom that she put her hands up so we could show her physical therapist. The people behind us assured us they were not going to buy theirs, and Mom thought that was very kind of me to ask. So thanks for making me think of that problem. I came out looking a lot more thoughtful than I would have been otherwise.
We actually didn't do any wheelchair return times because we made it to the headliners in DL early enough and I ran and got a FP for Radiator Springs Racers. But overall we did almost everything my mom wanted to do even though she only had about about 10-12 hours in the parks. It was very difficult to balance my mom's wants, my friend's wants and needs, and my own wants. (It was even more difficult when I found out about several other of my friend's needs and wants well after we arrived, and also I learned that I myself need some alone time in a trip or I will actually crack.) But my friend came away happy and I only broke down a couple times myself
so overall it was a successful trip!
As an aside, my other friend has some disabilities and the Cast Members were generally very patient and helpful with her, even when she misplaced things. At least 3 attractions CMs helped us out tremendously when we had some issues. (In retrospect, I probably should have checked more carefully to make sure everyone was handing the correct FP to the person taking them in busy and/or dark situations, but it hadn't crossed my mind at the time. Well, now I know.)
There really is something special about Disneyland for people with all sorts of disabilities. (Even mild social anxiety issues like I have.
)
Thank you again for the help, everyone!