Are there any rental car companies that will deliver vehicles to the hotel?

Yes and there is also transportation to parks and they even have a car service that takes you to other resorts locally.. we got the service for free I don't know if it is for all guests or free based on room

Yes. Talk with the concierge.

The concierge at the Sapphire Falls (inside the hotel just past the check in area) can help you with securing a car rental

Universal Concierge can help you get a rental car to the hotel.

No sure, but I saw few cars delivery and concierge helps the guests