Yogurt is also a healthy thing for them to eat, and my 4 week old ones love it. Scratch is also good because of the grains in it. The scratch they eat is only supposed to be 10% of their food.
All that vaccination stiff is optional, and if you use partly medicated feed they get the medication from that. If you decide to give them the vinegar, make sure that it is Apple cider vinegar with the Mother. The ones that say "with the mother" on it is safe for chickens. The vinegar boosts...