By no means to discourage you,
There is alot more to it than just setting up a koolade stand and going for it.
First check with your local health dept. They will have a pamphlet for what you are researching to do.
If you are looking at catering, and also setting up a vending site, I'm afraid you might be looking at two different animals, requiring possibly two complete different set ups and rules.
But start at the health dept, they will tell you what you need, and where you can get serve-safe or food handling training.
But before you begin, do all your homework, and C.Y.A.!!!!!
Expect to spend appx three times what you THINK your startup costs may be.