To what gonzo said it's 1 tablespoon apple cider vinegar (the organic kind, not distilled) to 1 gallon water.
They will need heat for at least 6 weeks until they feather out completely. They may need it longer depending on the temps in your area. It's good to transition them to colder temps gradually.
As far as what temps to start with, 95 is a guideline. I have found that most my chicks prefer the 85-90 range. However, I have some "tough" BCM's in the brooder that are 2 weeks old and they like the 70-75 range. In fact none of them are under the light. They sleep away from it. It is important for them to have the option to get away from the heat if they want. You can overheat them.
I buy a 50# bag of starter, and feed it until it's gone. For my 5 chicks I just raised, it lasted 12 weeks, then I put them on Flockraiser. I've found that there is less waste with Flockraiser then there is with layer feed. I just make sure to have oyster shell available for them. (the layers need this for strong shells) Scratch is like candy to chickens and should only be given as a treat, not a source of food. Some treats (like bread) I wait until my chickens are older before giving to them. If they are eating anything besides starter, you will want to make sure to give them grit. I don't supplement mine with grit as I have lots of small rocks outside for them to swallow. Once they are laying, you can give them all your household scraps with a few exceptions like raw potato peels.
By 16 weeks of age, you will want to make nesting boxes available and put golf balls or fake eggs in the boxes. This shows them where they should lay. (and they don't always get it right at first) Also make sure your roosts are higher than your nest boxes. Chickens like to sleep in the highest spot, so if your boxes are higher, they'll sleep in them. (which is a poopy mess for your eggs
)
I use pine shavings in my coop, it keeps everything dry, which is very important in keeping healthy chickens. I can buy a bale of it for $5 at my local feed store.
Most vets don't treat poultry. There's no regular check ups like with most pets.
Good luck and enjoy them!