It is a small group of attractions (Sea Life Aquarium, Madame Tussauds Wax Museum, Star Flyer and The Wheel plus a few smaller and less notable features....think arcades, 4D theaters, etc) surrounded by an assortment of restaurants. There is a large parking garage adjacent to the complex where you can park for free. They have a small train (similar to those you see at the mall) which families can ride for a fee.
I think most places in Orlando will be busy on NYE, if the crowds at the theme parks this week are any indication.
You can absolutely walk around the area without having to get back in your car.