I want to bring a "food truck" to the US. From mexico, but I need to know what permits do I need andwho I can talk to so I don't have any problems on the border.

Talk to US Customs or the border agency, possibly through Homeland Security.

The "Food Truck" will likely have to be rehabbed to meet very strict local board of health codes once you get it here...

As well as US Safety regulation on the vehicle.

How is it being transported ? Shipped, or drove?

But in general you just drive it here. Then title it, get it inspected by health dept, get all licenses