Dogs move around independently, head to bed themselves from 5PM onwards and are up and about from 7AM or so. You can play with them, feed them hotdogs and toss a football to them. Some of the dogs bark when you move over them to say hello. If you visit the site at night, they'll be sleeping. If you click on some of the dogs, you can see what they look like and get a glimpse into their personalities. I cannot tell you which dogs have a preview because they are now independently simulated.