Hello, I would like to help with your question.
Have you already explained to him that you think it would be best for him to begin atleast his basic college course work, as he makes the decision of exactly what he wants to do? It may be helpful for him to talk with an admissions counselor or academic adviser to help him get a better idea of what subject he may want to study.
The first question, the answer is yes, the second idea, we haven't done that yet and would like to try.
What is his response when you tell him that you think starting is a good idea? A adviser from a school that he likes may really help in getting him to see the benefit of starting his education now, even before he knows what he wants to do. By beginning his studies, this may allow him to have more access to get an idea of what he wants to major in.