I got away with it because I was on the edge of a tract rezoned as "industrial," next door to an abandoned chicken ranch, from past decades when it was rural. You definitely don't want a rooster in town. He'd drive everyone nuts.
Check your zoning to see if chickens are legal where you are.
Now, to the questions:
What do you feed chickens?
Chicken food, lol. You can feed them vegetable, fruit, and grain scraps from your kitchen. You can let them free range through the yard to eat bugs. That's tricky; many chickens will also eat your garden, although mine never did. I don't know why. You feed them "lay pellets" bought at a feed store, and perhaps some "scratch." "Scratch" is chicken candy, at least, they think so. :D Don't feed too much. They need the other more. A handful tossed down, in an area it's ok for them to "scratch" in, is plenty. I toss it down on top of weeds. They dig up the weeds scratching.
Some oyster shell or other form of calcium to keep their egg shells strong.
If they are free ranging, that's it, besides water, of course. If not, they'll need some grit available. Sand does fine.
how often do you feed them?
It depends on where they are living, what time of year it is, and the feeder I'm using. Mine free range all over the ranch, and I feed them a small amount once a day. That keeps them coming when I call, and also keeps them running around the place eating bugs, which I love. When I had them in town, they would follow me around the garden, and I'd toss them tomato worms. :evilgrin:
If they don't range, or in winter when the bugs and weeds are fewer, I keep a big feeder full, and just refill it whenever it gets empty. There are lots of kinds of feeders; mine hang from a beam, and have a lid; that keeps them from scratching dirt into the feed, and keeps them from accessing/fouling the top of the feed. I like them, but I may go to hand feeding every morning. The local packrats have discovered the feeders, and are spoiling them. Here is a pic of some common feeders:
When I kept a few in town, I would just go out every morning and toss some feed in a pie tin. As long as it doesn't get wet, it's fine.
How elaberate a shelter do they need? How much cold can they deal with in the winter? It rarely gets below the 40's here.
That's plenty warm for chickens. It sometimes stays below the 30s for weeks at a time here in the winter, never thawing even during the day.
Shelter? They need a safe place to roost, and a safe place to lay. They like to roost up high. There are all kinds of coops and roosts; you can google and browse for lots of options. When I was in town, I had a little metal storage shed with no door. I put roosts in it, and some straw on the floor. It was fine. In Georgia, where it may be hot and is probably muggy, make sure what you use has good ventilation.
Here, I have a small raised wooden building with a full sized door for me, 3 screened windows, and a little door for them. There are two poles for roosting, one lower and one up high. They want to roost as high as they can get, but my heavy birds can't get to the top roost from the floor, so one midway up gives them a "step." In the summer the windows let air flow freely. In the winter I cover them with a layer of heavy duty plastic to keep the wind out and the heat in; there's still plenty of ventilation. In Georgia, you'd need lots of airflow year-round.
They need a place they feel secure to lay. If they are free ranging, they'll pick spots that feel "hidden" to them. If not, they need a nesting box with some straw in it. A wooden box, about 2ft square, is plenty big. Bigger than mine. You can google and browse nesting boxes, too. Mine are recyled old goat feeders.
If they are not free-ranging throughout your yard, they will need a small "yard" attached to their coop so they can get outside. I don't like to crowd them; I'd give them a 10 X 10 for just a few birds, at the least. You probably want to roof that yard with chicken wire, as chickens do fly. You can prevent flying by clipping their wings; numerous directions exist on the internet. Birds kept in enclosed coops/yards need their houses and pens cleaned regularly. My birds, free ranging everywhere, get theirs cleaned out twice a year. They need, regardless, protection from dogs. Cats will generally not bother them once full grown. Hawks and owls will.
If you are going to be gone for a few days or a week, is there some way to leave feed and water with them for that period of time?
Sure. I fill up my feeders every Sunday, and don't have to worry during the work week. In the winter, it's dark when I get home, and dark when I leave. I do have to collect eggs in the dark, but that's all. The same goes with the water. The number of birds you have would determine the size of your waterer. In town, I'd suggest no more than 4 hens. A 5 gallon waterer will probably last a week.
And...last of all,since I know nothing...whatever else u think I should know.
Hens start laying at 5-7 months old, and lay prolifically the first year. They slow down after that, which is why efficient operations soup them and replace them every year. I'm not efficient; I keep them for their natural lifespan, and do not eat their tough old carcasses when the ancient biddies die. They will continue to lay, just not abundantly. I like to have at least one or two younger hens around to keep egg production up.
They are not pets, but can be socialized if there are just a few and you have the time.
I would talk to some people in Georgia, as I've never lived or kept chickens in your climate.