Hi Dave,
I recently started my own business, so I've researched many of these personally. I do retail and wholesale business, so my answers may not be as complete as you need. Yours sounds like a fun concept.
First of all, the City of Chicago doesn't want you making it out of your home, but it sounds like you're aware of that already. Every city is different, as I know some business owners in the suburbs that are converting their basement into a commercial kitchen. Kitchen Chicago is the only one of its kind in Chicago, unless you personally know someone who would rent you kitchen space. I rent from them myself, and can say that Alexis (one of the owners) is probably the one of the most helpful people I've ever worked with. Not only is she extremely flexible, she'll give you pretty much any assistance you ask for. She's held workshops for us in the past, showcasing packaging, for instance. She requires that you sign a contract with her, and have 1 million in liability insurance, which she also provides a contact for.
You'll want a business license, food safety certificate (for both the city and the state), assumed business name (if the name of the company is anything other than your name, "Dave's Catering", for instance), federal employee identification number (FEIN), and a state tax ID. There may be more, but that's all I can think of off the top of my head.
It took me quite a while to research this, and in the process I lost time and even money, by making a few bad decisions. I recently came across SCORE, which is a group that helps small businesses. They're all retired professionals (many of them multi-millionaires) who donate their time to help people get headed in the right direction. They're affiliated with the SBA, so can give you pretty much any sort of assistance. I would highly recommend going to them - their counseling is free, confidential, and repeatable. Be warned, they will ask for a full business plan
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However, if you don't have that completed or need assistance, they will also help you with that. It's definitely not a hand-holding organization, but they will use their experience to help you along the way. I took a few great workshops there (about $30 each) which really helped me.
Feel free to ask any more questions, and I'll help as best I can. Good luck!
Katherine
Everyone has a price: mine is chocolate.