I have three acres, and when my hens free-ranged, they ranged the WHOLE three acres and sometimes even into the neighbor's land. I've heard that chickens only go 200 yards, but it hasn't been true of my flock. They are now confined to a large, fenced yard.
Predators are unique to each area. Personally, the only problem I've had is with hawks, and once a stray dog. Coyotes haven't bothered my chickens, though they do come near our property during the day sometimes. I don't have any problems with raccoons or foxes. My point is, you will need to evaluate your predator problems when you move to your new house.
My chickens range a very large fenced yard, and covering the whole chicken yard with netting is not an option. I read an old article that suggested running strands of fishing line above your chicken yard. The hawks can see it, and they won't fly between the lines. The article claimed that the hawks develop a memory, and after a while they will even stop hunting over the protected area, even if the line is no longer there. I placed each strand about 6 feet apart over most of the yard and it worked very well for me - no hawk problems even though I frequently saw the hawks sitting above my neighbors' chicken coops. The problem is that the line sags in the winter with the weight of snow, and you end up having to pick up nearly-invisible strands of fishing line in the spring. If you try this, I would recommend something sturdier and more visible to humans, like a thin rope of some sort.
I had hawk problems in my first winter here. I got two guineas the following spring and haven't lost a chicken since. One day last year I was sitting in the dining room, watching the flock from a window. Suddenly the guineas started screeching and the whole flock ran to the coop. A few seconds later I saw the shadow of a giant hawk fly over the chicken yard. Proof enough for me!
Guineas, especially the females, are extremely noisy. They can be challenging to train to stay home, and if they aren't sufficiently bonded to their coop, they will eventually fly away. It is absolutely essential that you get them as day-old keats. Do not buy juvenile or adult birds - they will not bond with your property! They do range quite far, though mine tend to stay with the chickens in the fenced yard now that the flock doesn't free-range.
I have a male and a female guinea. As I said, the female is extremely noisy, but the male can be a bully to my chickens and he is very protective of the female guinea. He will chase the chickens away from food or out of the coop if he wants to be there with his mate....They are definitely at the top of the pecking order. They male is quite noisy for about ten minutes at dusk when he is calling the hens to go into the coop (yes, he really does round them up, and he won't go inside or stop calling until everyone is in).
The benefits are that they do an excellent job of protecting the chickens, and they are great for insect control. We don't have a flea or tick problem to speak of on our property. We haven't put flea medicine on our dog or cats for two years, and even the barn cats don't have fleas or ticks. The summer that the flock free-ranged over our property, I didn't see a single Japanese beetle, either. That's quite a feat here!
As far as I'm concerned, the benefits of having guineas outweigh the negatives. I live on three acres in a rural area, but if your new property is in town, your neighbors will most likely complain about them.
I wouldn't be without my guineas. In fact, I'm planning on buying a few more in the spring. A book that I found to be very helpful was "Gardening with Guineas". It has great information for the beginner.
Laura