You can fence off a part of the yard for the birds beyond what the run will be. Any and all vegation in the run will be annihilated with in days. SO, it won't be totally free range, but it will be a better foraging area than none at all. Terriers... Well terriers are terriers and if you train them that they are NONONO! Then you might be ok. Or build a dog run too. My cats don't bother with the chickens, not even the chicks. My chickens... well a few actually terrorize the cats. LOL, and that alone if funny to watch. My brooder babies were in a covered brooder, so the cats could not get it, but they sure loved to sit on the outside looking in, or on the top looking down. Kitty TV... Or window shopping. Maybe thinking, "So, this is what my kibble looks like before they cook it..."
ISA, RIR, Leggerns, NH... From hatcheries, from my understanding, and I can be wrong, someone will correct me, are bred with the intention of constant egg supply. They can be wonderful birds. I loved the little leggern I had till my dogs happened to her. The problem too with hatchery birds, is if you are going to use them with the intention of getting eggs everyday and through the winter with light supplementation, you will need to change out your birds every 18-24 months. Not necessarily change them out, but be ready to add new birds when the currents reach about 18 months. They can be worn out quickly if they don't get a break as nature intended, and just STOP all together, and you will be asking, "Why aren't my birds laying?" Thats ok, if you plan on stew potting them. I am hoping to get more than 2 years out of my birds. So, I only add minimal light in the winter.
Neighbors do hatchery birds. Normally leggerns and red varieties. This time around though,they also got orps and australorps, and a few GLW/SLW for added color. He says that so far most of them are laying, gets nearly 2 dozen eggs a day. His plan is always the same. He keeps the flock for about 18 months then starts to sell out the ones who are not laying daily. He also has 14 hours of light through the winter. He of course has to do this in order to meet his egg demand at work where he sells. I do not have to do this. I have 4 hens right now who are at that age. Two are molting, and even though they are, I still get an egg every couple of days from them. Light molt. I have 2 that are broody, and one of those broodies is molting. LOL. I have 12 hens that are actively laying. I don't always get 12 eggs. On occasion I will get 13. BUT, I only need the eggs to feed my family. I do sell them though if someone comes to the door.
I guess what I am saying is, if they are just going to be for your useage, how many eggs a week do you really need? Go with this need in mind, and you can then pick the types of chickens you really want. I have only six girls of my twelve that lay EVERY DAY now. Some will lay every other, or two days in a row and then skip a day. This meets our needs. We really only eat about 2 dozen a week. SO, I have breeds that I like, meet those requirements. Get a few that are serious layers, the afore mentioned, then get a few that lay 4-5 for variety. Want a colorful basket for the counter? Get some EE/Olive eggers. Darker eggs like chocolate colored shells, get Marans...
I have Faverolles and Faverolles crossed with NH, Light Brahma, Wyandotte and an I have no idea bird, who lay pretty darn good nearly every day. My cochin bantams and silkies when not broody lay every other or 4-5 depending on the bird. I have a LF cochin who lays everyday. My egg basket colors range widely. I have white, pink (or tinted), light tan, to medium speckled brown. I have one hen who lays every other day or so whose egg shell has a purplish sheen to it and one green egg layer.
