A coop would solve most of your problem. Letting chickens roost in the open is an invitation to predators for easy meal. That said, we all have different ways of caring for our animals. Yes, a dog would keep most predators at bay in your fenced in 1/3 acre lot. It would need to sleep outside in that chicken yard.
There is not a breed of dog that automatically does not chase chickens. It takes training and understanding of the dog. Any dog with the correct handling will not injure the other animals you care for. Any dog will protect it's territory. In your case that would be a 1/3 acre fenced in back yard. The only requirement for the dog would be that it could handle, scare off, a raccoon. Meaning it shouldn't be smaller than the predator it's deterring from an all you can eat buffet.
There is not a breed of dog that automatically does not chase chickens. It takes training and understanding of the dog. Any dog with the correct handling will not injure the other animals you care for. Any dog will protect it's territory. In your case that would be a 1/3 acre fenced in back yard. The only requirement for the dog would be that it could handle, scare off, a raccoon. Meaning it shouldn't be smaller than the predator it's deterring from an all you can eat buffet.