It wouldn't hurt to get a IDP the police have always said to me "very good you have" when I have shown mine but a normal driving licence is accepted. As for renting vehicles yes the old con of screwing the customer for damages does happen but there are reputable hirers as well, personally I would never hire a vehicle from the beach road. I always used Braun rent a car before I bought one and had no problems, good cars, good service, european management and free drop off pick up from your hotel. Click
here for link.
Just noticed on their website they say free drop off/pick up if booked on the internet but I never did it that way and never got charged so would think you could get this if you asked.