start with the local health dept. Generally stainless for counter tops is good. The real key is everything should be NSF approved. Hand sink, approved water system. A lot depends on what you want to vend. If you want a fryer then you need hood vents with appropriate CFM's and a fire surpression system. Just having a 3 bay sink isn't enough. They measure the sinks to calculate if your hot water heater has the capacity. Be prepared to upgrade.
Best bet is work with the HD on a plan before starting anything. Pick out equipment and before buying get the specs to the HD especially hot water. And that's just the start. If you are cooperative with the HD they generally will work with you and help. If you piss them off then it's a real long road.
Retired competition cook. BBQ mentor.