There are a lot of good breeders in Florida, but most breeders will also ship. :] Cruise around a bit, some good bp breeders are;
www.baileyreptiles.com Tim and Monica Bailey
www.8ballpythons.com Adam Wysocki
www.bhbreptiles.com Brian and Lori (I can't spell his last name for the love of me)
Those are some good breeders that are big. There are a lot of small breeders on here though as well. Breeders are always a much better choice than pet stores. Don't get advice from them either.
They do not need any vitamin supplements. However, it is important to get their husbandry as perfect as possible with that care sheet above.
Reptile shows are a good place to see a lot of breeders as well. :]
Basking lamps are useless. If you want one for appearance, get a florescent tube light that doesn't emit heat. Basking lamps suck out humidity and make it terrible in an enclosure.
For a baby ball python, you can get tubs (if your not looking for appearance) or you can get a 10 gallon tank. Then level up to a 20 gallon after 1-2 years. Do not go right to a 20 gallon for a baby, it is too much space and is stressful for the animal.
For heat, one thermostat with a proper UTH on the warm side should regulate temperatures properly if the cage isn't overly large. You'll have to get a couple probe thermometers and hydrometers as well.
For food, I suggest switching to f/t (frozen) or asking the breeder to switch to f/t for you. Unless you plan on breeding your own mice and rats, you will have size issues and it will be very expensive from pet stores. You can purchase frozen in bulk from many online stores and pick any size of rat (I suggest feeding rats starting at a rat pup for a baby bp because they are fuller and have a better size capability for ball pythons).
Good luck!