It's been a short while since I've had chickens of my own. My ex kept custody of the last batch and I'm renting now. I have shared space with chickens for a goodly portion of my life, though, and I plan to again. Currently, my landlord has a small flock, and I've been interacting with them.
I do love chickens, I don't always love roosters, but hens are nice to have around. They are very social, and I've been told recently that special diapers are available so that they can even be house pets. I won't go there, I'm happy to leave them in their own house, but I'd certainly rather have chickens around than not. They are very easy to house, they lay yummy eggs, and you can't beat them for doing your composting for you.
Chickens will eat ANYTHING! Even each other! Healthy animals are safe from chickens, and they don't usually attack another chicken unless it is injured. This is one reason that larger growers often use red lamps in the hen house, to disguise the presence of blood on a wound. The other hens will peck at an injury until they kill the chicken.
Chickens can easily subsist on what they find ranging around, grass, bugs, seeds, bugs and more bugs! They do an excellent job of cleaning and de-bugging a garden between crops, but can't really be trusted in it during the growing season. Most will scratch up your seedlings, and peck at your produce. (There are exceptions, check the various breeds for them if you desire that quality.) However, after harvest is over, let them in to till and feed! It is usually good to augment what they get with "scratch grains". I like to give laying hens some "laying mash" feed and keep some oyster shell or other source of calcium available. Chickens also use grit, sand, or small pebbles to grind up food in their stomachs. (No teeth, remember?) Most of the time, they pick up all they need from the ground, but some people also furnish some grit. Many people will also grind up eggshells, toast them, and feed them back. Just don't give them plain broken eggshells without doing that to disguise them, they can develop an appetite for their own eggs!
Chickens are easy to house. There are any number of simple plans for coops and chicken tractors and so forth out there online and other places. The tractors are cool, you can move them around in your yard or garden, let the chickens graze a different spot every day, and still keep them contained, if you wish. Some time back I made a coop from an old metal storage building. It was one of those small ones made from a kit. I added flap windows screened with chicken wire, closed the sliding doorway with more wire, a people door and a chicken door, added a ladder-type roost and a shelf. On the shelf I tied several of the enclosed type cat litter boxes we picked up for free on curbs, or cheap at garage sales. Thoroughly sanitized and stuffed with grass they made very good nest boxes. My favorite nesting material for the nest boxes is dried grass, or loose hay without stalks or other stiff material. Anything smaller gets scratched out by the hens. All of it will be scratched through and out in time, but the grass lasts longer and seems more natural to me. Occasionally we added a fake egg to encourage real donations. More hay, dry leaves, or other bedding material went on the floor. Cedar shavings, while a good deterrent for many insect pests, have been known to cause problems for some chickens. You might go easy on those, or alternate with pine shavings.
Back to the coop! I added a water fountain of the inverted bucket type, and a couple of hanging feeders, all garnered from a farm sale, and we were set! We built a pen around the coop for extra security, and let them range free most of the time when we were home. The pen had chicken wire six feet high. The whole area was under a large tree for shade, we didn't put a top on the pen. Most of the chickens would stay in the pen if the gate was closed, those that didn't got their wings clipped. We had occasional depredations, mostly from dogs, so we did shut them up at night in the coop.
The presence of feed did draw mice often, which also drew snakes occasionally. We often captured "chicken" or "rat" snakes that were eating mice and eggs. One of them was over six feet long! I also found a small rattlesnake under one of the hanging feeders waiting for mice. That wouldn't have been too bad, except that it was the same place my toes usually went when I was adding feed! I made a simple snake catching loop to use in that process, but I finally got to where I could pin one down and catch it by hand.
After all the basics are done, it is a simple matter to check feed and water daily, and gather eggs. I found that four to six hens will usually lay enough eggs to supply a family of four, with a few extra eggs for giving away at times. A rooster isn't really necessary for the laying part, except that you'll hear him often taking credit for it! The rooster IS helpful for discouraging many predators, and will raise an alarm. They do NOT just crow at sunrise, and neighbors, if you have any close, will quickly disapprove! Most cities actually allow chickens to be kept in the yard, under varying restrictions for health, etc. BUT, many don't allow roosters for the noise issue. When I lived in the suburbs in Round Rock, Tx years ago, it was allowed in the city and the subdivision, but I still kept my neighbors supplied with eggs, just in case. Many times, even if it is a "gray area" issue, the authorities just won't bother if no one complains. It's also best for the neighbors, you, and the chickens as well, to clean out that house/coop and pen on a regular basis. Shovel that directly into that compost pile you've been neglecting along with the soiled hay, etc.
Like all birds, chickens don't have sphincters. They cannot be trained to NOT defecate wherever they are. This includes your car, your sidewalk and your porch. Therefore, you may have other fencing issues. That garden in Round Rock had a small pen, about twenty-five square feet, and a small low coop with built-in nest boxes accessible from outside the pen. It wasn't much more than one of those chicken tractors, although not portable. It easily housed four hens, and was next to the garden, so we could weed the garden, or capture pests, and toss them over the fence. All our household scraps went directly into the chicken pen. A great Permaculture technique is to build a chicken "moat" around the garden. Make it wide enough that a grasshopper will have to take two hops to cross it. He most likely won't get that second hop! It was always fun to watch the hens running side to side to snag a flying june-bug when it got to them, like feathery outfielders chasing a fly ball!
Another garden technique is to have two gardens sharing one hen house. One year one of the gardens is the chicken pen, and the next year the other one is. Each side bug free, composted, and ready to go when its turn arrives. It is sound Permaculture practice for every element to serve more than one function!
It's not uncommon to find grown hens and roosters for sale, but a greater variety are available and much more cheaply as chicks. Temporary housing, called a brooder, is easily made to keep the chicks warm until it is time to turn them out. The idea is to furnish all the basics, food, water, and above all warmth. They are babies, after all. Once again, easy plans are available online and in books I've noted below. You can even go a step further and incubate your own eggs. It is not that hard, whichever way you go. Most farm stores, feed stores, Tractor Supply, and so on will carry chicks in season.
When it comes to breeds, hands down I prefer Rhode Island Reds. They lay very good, brown eggs. Rhode Islands are classed as a multi-purpose breed, good both for eggs and meat. There are many, many, breeds available, and all have their good and bad qualities. The Reds I've had have been easy to care for, good grazers, good layers and friendly birds. The hens don't lay on an exact 24 hour schedule. The hens would usually average a bit less than one egg each day, depending on the time of year.
Other fowl are available. The only ones I have much experience with are ducks and guinea fowl. Ducks lay really good eggs, and usually won't bother growing garden plants. Some breeds especially are death on slugs, if you have that problem. Most ducks I've had though, require LOTS of clean water. Any amount of water they have access to they will quickly foul. Remember what I said about sphincters? Water seems to turn it loose on ducks! I kept a wading pool filled for our two ducks, it had to be changed pretty much daily. Those great eggs they laid were also seemingly laid at random without bothering to find a nest. We would just find them wherever they had been walking. I did put a couple of nest boxes on the ground for them, and they did use one occasionally.
My grandmother always said, "keep a few guineas, they make good watch dogs. They'll warn you if anyone comes around!" It's hard to know if that was true. Ours were never quiet! The ones my landlord has now are always raising a horrendous racket under the bedroom window early in the morning for apparently no reason whatsoever! Guineas do have an apparently deserved reputation for being voracious on bugs, even more so than chickens. They've even been known to eat ticks and scorpions. We've personally noticed a huge decrease in the scorpion population around our place here, and very rarely do we find a tick. We never tried guinea eggs, and I don't personally know anyone who has.
That is a good portion of what I can say about chickens. By no means an exhaustive study, but a place to start. I would certainly recommend a few chickens to anyone with a little space to put them. Check out my links, and enjoy!
The free-ranging chickens are a valuable part of pest control, as well as composting.
I select a pile, it really doesn't matter much which one. I move the top layers over to the adjacent pile until I reach the good compost. It goes through a mesh screen into the wheelbarrow. Whatever doesn't go through the screen goes back on the pile. 
