I stayed in LCQC last Nov and it was fabulous. Booked directly with the hotel and they upgraded me to a junior suite in El Murmullo which is an adjacent private residence. I strongly recommend you do that - given you are going in the low rainy season, chances are pretty good. El Murmullo is basically a private villa in exactly the same architectural style as the rest of the hotel but only has 4 rooms and has its own butler and chef and gorgeous swimming pool. We only shared the villa with one other couple when we were there and had the pool to ourselves. The main hotel is just across the street and you can go any time you want but guests from the hotel do not have access to El Murmullo. Bill Gates stayed there a few years back.
You won't need a car - there are plenty of restaurants within walking distance on Playa La Ropa (incl the ones at Villa Del Sol, the other luxury hotel in Zihua) but frankly the food in LCQC is the best in the area and the restaurant is regarded as one of the best in all of Mexico.