I've driven twice to Ronda - both times for 3N stays. I enjoy driving and I have driven a lot on mountain roads.
I got lost leaving Sevilla once, until I finally got on the right multi-lane limited access highway. I'm not very good at navigating in general and worse when driving at the same time. Many rental cars in Europe do come with GPS but don't count on it. Bring from home. I finally bought a Garmin with European maps and a smart phone and use Waze. I'm sure I'd had been fine with either. Once well out of Sevilla, it's mostly a two-lane highway through the hills (and I never got lost). All the roads I drove were in good condition and the curves were well graded. It's also very scenic and there are pull-outs where you can easily stop to admire the view and take a photo. All the hill towns, including Ronda, are off the main road. Some of them can be very difficult to drive into, because of narrow, steep streets, sharp corners and parked cars. However, those villages are small, so you can park and explore on foot. Leaving Ronda, you'll have some hills to drive through but then it's a multi-lane divided highway to Granada, where you may want to drop the car and then take a taxi to your hotel. The old city center can also be a little tricky to drive in.
In Ronda, most of the city is easy driving. It's surprisingly flat. The oldest part of town has narrow streets with sharp corners and the side streets always seem to have cars parked where they shouldn't be, but if you go slowly and carefully, it's not a problem. Some hotels have parking spaces. There is an underground lot in the center, close to the bridge and the bullring. I've only been to Ronda in winter, never had trouble getting a space there.
If you decide to rent a car, spend 1-2 nights in Ronda if you can fit it in your itinerary. Then visit Arcos on your way to Ronda. There's a big parking lot at the foot of the town and then a steep walk or a shuttle ride up. It's well worth a few hours. Then drive on to Ronda for the night. If you stay 2 nights, you'll have plenty of time to enjoy Ronda's sights or to spend the day visiting other hill towns.