I'm a wheelchair user, but younger and have a lot of stamina. My last trip to Paris I stayed on the Ile de la Cite, in a VRBO apartment. I was pleasantly surprised at how many dropped kerbs/curb cuts there were, although a curb cut is of little use when the sidewalk is blocked by parked cars, in which case I stay in the street.
Random mobility impairment observations about Paris:
1. Metro useless, except for a couple of stations on Line 14.
2. Maybe people are considerate of older, mobility impaired people in the metro, but that wasn't my experience - I was rushed, pushed, and jumped over by people who were inconvenienced by my presence.
3. Cabs useless - every time I tried to hail a cab, it drove off fast as soon as the driver saw the wheelchair. I did take a couple of cabs, by getting hotel doormen to hail the cab for me while I hid.
4. Being a wheelchair user in long lines for tourist attractions (Louvre, Musee d'Orsay, etc) is good - generally some staff person would come fetch me out of the line, escort me to the entrance, and let me in for free.
So I walked (pushed) a lot, and stayed very local.