We keep three brown hybrid hens in a subruban area, we have a reasonable sized hen house and run. We do let them in the garden sometimes but they make a hell of a mess of the flowerbeds etc (and means kids have to avoid the poo!)
My advice would be to try to find a local place that sells chickens and the stuff you need for them (e.g. feeders, straw, food- layers pellets/mash and grit, corn for treats etc., anti-mite cleaner for house and equipment). We have a great poultry centre nearby, maybe we are lucky, but they can advise on all sorts of issues too, and provide food mixed with wormer twice a year.
There are many things that you learn as you go along but I found their advice and a good book useful as there are also a few urban myths about keeping chickens that can cause health problems. For example that it is ok to feed them on scraps, while they are ok for treats it is really important to give them a proper diet of layers pellets or mash and make sure you don't give any treats until after lunch time so they have filled up with correct food first. Some foods are very warming and should not be given on a hot day, like corn. Some things are even poisonous, like raw potato or even chocolate (i think).
It is important to get your chickens from a reputable place where you can see they are healthy and to check they are immunised, so i wouldn't reccommend getting them from any old place.
Hens that peck each other are possibly bored, may help to keep them active with hanging up cabbages or digging over their run so they can scratch for worms etc. It could also be to do with lice or mites. It needs attention though as some can turn cannibal and kill each other (in extreme cases).