Hens generally start laying at 22 weeks of age and will lay around 260 eggs a year, decreasing by about 20% each year. It's up to ou to decide when prodution is unacceptably low. Commercially, they will do one season then be sold on or despatched. We, on the other hand, have some pensioners who haved laid an egg in living memory.
Production falls off in the winter unless artificial light is provided and picks up again in the summer. You won't get much meat on a spent layer.
Commercial meat birds are ready for killing from about 10-12 weeks.
Cockerels of dual purpose large fowl will take 20plus weeks to reach a decent weight.
Hope this helps.