All vendors need have a license, a food truck also has to in a lot of cases negotiate for a spot to park in. As I understand it takes a long time to get a license (months). I have no details since I am not yet in the island, but others here may.
I don't see why would Tourists not want to buy from you. Expats have a lot of businesses in the island.
All purchases have been mostly in cash in the island, they just passed a law requiring that businesses also add a form of electronic payment. I am sure there are some exceptions based on the amount of business or size. One of the sore spots have been clinics only accepting cash, the government is trying to change that.
