A chicken farm is usually a small commercial oriented business which should have a large abundance of chickens ranging from 100 to 2,000 depending on the size of the farm.
Chicken Genocide
Growth hormones to make them bigger. I advice you to start buying natural or organic because the hormones can affect you.
Chickens can get to about 15 years if handeled correctly, but they would only lay for about 7 years.
This website might be helpful: http://chat.allotment.org.uk/index.php?topic=13725.0;prev_next=prev