I would start by talking to the local health department. Your local rules are going to drive what resources you will have to have on site (commissary, etc....) and those rules vary greatly across the USA. If you keep the health inspector happy, your career will be much smoother.
Incorporating into at least a LLC is a great idea as would be obtaining liability insurance. There are lawyers who specialize in food poisoning just like there are ambulance chasers for auto wrecks. Even if you are not the cause, defending yourself and your company will not be inexpensive if someone tries to claim your food was bad and made them sick.
In most states you can file for incorporation without a lawyer if you know what forms to use. I see you are in Waukee (Iowa?) and I have no idea about the process there. I paid about $700 for a "C" corporation I set up in Georgia in 1991. It runs me $50 a year to keep the registration current. I'm sure the fees also vary widely in other areas.
You already mentioned licensing, which is a must. A plus of licensing and having a state reseller tax number issued to your business is you can buy your materials in bulk and at wholesale prices. I'm sure there is a large wholesale store in the Des Moines area.
Also make sure you either use an accounting service or at least get software like Quickbooks and keep your receipts for expenses. It's not rocket science to run a business, but it has to be done right or you will have one government agency or another after you (ie, health department, tax man, etc...)
You might want to see if there is a similar business who would give you advice. If you could find a catering or BBQ service who works another area and they are willing to help, you could be ahead of the game learning from their success and mistakes. Might even be worth paying someone to mentor you so to speak.
Not to rain on your idea, but you might want to look into how the new food labeling regulations will fit into a catering start up. It can get pricy to have food tested every time you change the menu, the rub, the recipe, or use a different meat source. The new laws coming on line now and later this year require all sorts of calorie and other counts data be displayed on your menu. If the big boys are bitching about the costs, I can only imagine what this will do to the little guys and start ups. Once it's a business instead of a hobby there are all sorts of rules that you have to comply with and they all cost money. Hell, even the Affordable Health Care Act (Obama-care) will have impacts on your pocket book as a business owner.