I've done some research on types of breeds that suit my climate, and I've read the article on what to look for in a chicken when you are buying it (to make sure it is healthy), but I had a few more questions. 1. Should you only buy from reputable breeders for backyard egg layers? There is one commercial egg place near me that sells chickens, otherwise I think it is mostly people who just have extra chickens, or have decided to hatch some eggs selling them. 2. Should you ensure that the chickens are vaccinated? If so, what against? 3. What age are chickens able to be integrated with the rest of the flock without requiring extra food/care? 4. Is there are particular breed of chickens who are less prone to illness, or any particular breeds to avoid? (after having and possibly losing a girl to being egg bound, I would prefer chickens who are known to be rather hardy, if there is such a thing! 5. At what age can you tell the sex of a chicken? (So I can avoid accidently getting a rooster!) I may have some more questions later on! Thank you!