I agree with Lee that Hotel Atlantis is ideal .... Try to get one of the rooms with a balcony view of the Caldera... this may be possible in November. Atlantis is one of the more venerable hotels on Santorini, and while not flashy, has a stately quality. It's right next to the Cathedral. I remember recommending it to a couple in their 70s; the wife couldn't manage stairs of more than about 6 steps, and the husband couldn't lift anything heavy & thus wanted a staff that could carry luggage. On their return they wrote me a delighted report. It seems they were on their balcony, and there was a wedding in the cathedral which spilled out into a celebration in the courtyard... a member of the wedding party saw them looking on, and beckoned them to come join the fun, which they happily did. They also had a good experience driving around the island, and I believe Atlantis also has room I believe for a few rental cars by the hotel, unusual in Fira. I see the ever-helpful Lee has already given you key info about Car Rentals.
To continue stair-avoidance strategies: In November, the sun will be setting VERY early -- about 5:15, time for a little drinkie while watching... and the Atlantis lobby has caldera-view seating right by its little bar. Then for dinner, you can choose any restaurant doesn't involve steps DOWN the cliffside or UP to a terrace -- and the hotel desk will know the best choices open in November.