1) Are you incorporated? If not, do so NOW! Form a Delaware LLC - costs about $400 to form and $250/year (annual franchise tax to DE of $200 and $50 to them to act as your registered agent) to maintain through these folks who I have used for years and recommend highly:
http://www.delawareinc.com/. You can do it all online with a credit card. If you don't know why you need to incorporate, research that online as I don't intend to write a free dissertation here.
2) Insurance: your LLC will need a general liability policy from a reputable company. "Google" variants on the phrase 'food cart insurance' and you'll find plenty of leads, advice, and info. Research, research, research, then shop, shop, shop. I would think that a liability policy with an additional $2,000,000 "umbrella" should cost you from $500 - $700.
In 1993 I started a fast food franchise that opened with $35,000/week and settled there. I had gone to a "country club buddy" and, trusting soul I am, paid $12,000/year for property & liability from a "Brand X company". After two years I was bored one day and shopped the coverage. The typical quote was $2,500 - $3,200 for equal or better coverage. I chose a $2,700/year policy from the Travellers. When I spoke to my "buddy" about this he blushed, shrugged his shoulders, and said: "Insurance rates vary." No sh*t, Sherlock!
Good luck!