We are like Jacki and Andrea. we rent for the entire trip. Really depends on what you plan to do. We also go to Baby Beach, Arashi and Malmok to snorkel. Go to dinner almost every night and hit different casinos in the evening. Wife is a shopper as well. We figure that we would probably spend more money on cabs for transportation than on a rental car. Even if you are just taking a cab to a restaurant it might be $10 but that is one way without tip, plus the wait time. Just more convenient for our style. We met a couple on our second trip that had stayed at the Divi AI for 12 years and never left the resort. Different strokes for different folks.
We are not the type to stay solely at the resort AI or not. I have to become what my wife refers to as "The Mule" ... Carrying all her Gouda cheese!
For restaurant reservations if you have someplace that you really want to dine then make the reservation. I usually make ours 2 weeks out. My preference is not to make reservations. It's not usually an issue since we enjoy dining out early. If you are interested in Carte Blanche than I would suggest reservations a few months ahead.