To Rent or not to rent a car?!
I highly recommended not to rent a car and use public transportation, instead!
It is a small island and you can reach anywhere by bus within about 1 hour with a few euros.
If you drive a car, you may not be able to enjoy the nice views as driving in narrow sreets needs full concentration..
Besides, you would need a bit of luck to find a free parking spot closeby to the landmarks...