Each locality has its own rules and regulations concerning the license to assemble/right to assembly (which has to do with people gathering, not putting parts of a machine together). If you don't have a food establishment permit, or you're in the wrong zoning area for your art gallery/live music, that could be the reason for the fire marshal's reaction.
To get to the heart of the matter most quickly, speak to an attorney in your area who deals with small businesses like yours -- they'll likely know exactly which permits you need and how to file them expeditiously.
Nina L. Kaufman, Esq. is an award-winning New York City attorney, edutainer and author. Under her Ask The Business Lawyer brand, she reaches thousands of entrepreneurs and small business owners with her legal services, professional speaking, information products, and LexAppeal weekly ezine. She also writes the Making It Legal blog.