A friend asked how hard it is to raise chickens. I answered as follows, based on my research into the subject (not based on personal experience since I'm not allowed to keep chickens where we live inside the city limits *wink*)
Chickens must be the easiest and most productive animal to raise. They need a run, a coop, food, and water. Other than the materials and labor to set up the run, coop, etc... The only maintenance required (assuming the run is big enough and you setup the coop correctly) is refilling the feeder, and cleaning out the water dish on a regular basis to keep disease at bay. A poorly designed coop will require regular cleaning, and a run that is too small or poorly placed will require hay or other composting material and semi-regular mucking out.
A rooster is NOT required for eggs, although some people claim that only fertilized eggs are worth eating.
Set the run up on a slight slope, with the high end having easy access to throw in compostable materials (food scraps, lawn clippings, garden waste, etc...) and the low end having an easily removable gate to shovel out the lovely rich compost / fertilizer they produce. The ideal setup would have a drop of a few feet from the low end into a compost bin where the mixture of chicken poop and compostable material would drop and cook into a rich but usable material for your garden. Chicken poop is to rich to use directly, so it must be mixed with other materials (they do that naturally in the run) and then let set for some time to cook.
Setup the coup OVER the run (or lifted up on stilts) with a chicken wire screen under their roosting perch and a very slight slope (darn near flat) from the nesting boxes down to that screen and just a strip of wood to keep the eggs from rolling out onto the screen. Then the nesting material (sawdust, etc...) will randomly migrate out and down through the screen, they will poop through the screen while roosting (which they do a LOT) and that poop will be mixed with compostable materials in the run as they scratch through it. Chickens have a close relationship with their own poo. They let bugs, maggots, etc... grow in it and then scratch those out an eat them.
If you build your garden beds high enough and surround each bed with a waist high fence, you can let the "girls" out once in a while to clean the back yard of snails, bugs, spiders, etc... They don't like to eat ants, and they DO like to eat your best garden greens in the most destructive and wasteful ways possible. E.g. just the main root from each pepper plant.
Smell: Really not as bad as people think, assuming the run is large and either setup smartly or kept clean with manual labor. But there is a bit of a whiff on hot days...
Flies: No matter how clean you keep it, chickens shit, and you will get flies.
Spiders: Spiders follow from flies. We have more black widows per square foot than any place I've ever lived.
Garden and grounds: They WILL get out, and they WILL destroy something you lovingly planted. They like to scratch or dig up flowers, veggies, etc... Any area that they frequent will be laid baron by their constant digging for bugs and the overly rich power of their poop.