We are planning to move back to Germany. We'll live and work in a small City in border to Netherland. Is it possible for my teen boy to study at Dutch international school?
It is not possible because your teen boy is young and you cannot leave him alone in the Netherlands. It's better to find another school for your teen boy in Germany.
Yes, it is possible for your teen boy to study at Dutch international school. Because he goes to a Dutch international school, it is likely that he will learn the English language and be able to do business in the country.