>Dumb question: I only speak English. Don't they/you speak Dutch there?

Business language is usually English. Since almost all Dutch people speak English this is the common factor here, because we also have lots of US citizens living in Aruba. I know plenty of people which don't understand any Dutch and they don't have any trouble with that. But you are right, official language in Aruba is Dutch, but that concerns mostly legal forms. A lot of the legal transactions are bi-lingual.