You can choose to vaccinate or not. If you do, I suggest you search for what diseases that are common in your area and vaccinate accordingly. There are many kinds of vaccines out there you can administer yourself. Some vaccines are given at hatch, and some later on. You can purchase the vaccines at my favorite place
http://www.jefferslivestock.com. Example: I did my research and found only new castle, broncitis, and fowl pox are the most common in my area. The fowl pox vaccine is only supposed to be used if the disease is present in my flock (which it is not) according to the label.
When worming, you are not supposed to eat the eggs or meat for 14 days after the last day you administered the medicine. so, you will not want to treat laying hens while laying or slaughter meat birds during this time. I will use wazine17 if i have a worm problem.
Usually vaccines come in 1000 doses and cost about $6 USD and up.
You might also consider purchasing a mite/flea/lice product like poultry dust, poultry protector in case of bug infection.
If you buy chicks, i would suggest you get any vaccine that is offered and feed medicated chick starter to help prevent cocci.
I hope you find my suggestions helpful and welcome to BYC!