To get around, renting a car is the most convenient option. Alternatively, Uber and Lyft has a strong presence in the city. Many points of interests are easily walkable- especially Winter Park!.
If you want to include more parks/attractions/activities in the itinerary, consider adding more days to your trip. Conversely, if you want to have a more relaxed trip, consider removing a few of the more time-consuming activities from the itinerary.