You did not ask about the practice of naturopathic medicine in an open ended way. You asked specific questions for which it seems you already had decided upon the answers. There are indeed speciality societies within the profession, and board certification is available in some states for these specialties. Well, not in the real world. Most truly sick individuals have chronic illness.
Hospitals are generally where acutely ill and injured people go.
Were you a physician, you most likely could make this distinction more easily. Most seriously ill people are 'walking wounded'. And of those seriously ill people who were at some point hospitalized, most continue to be 'sick' outside of the hospital environs. If all you want is to be right about what you already believe, then you should have no trouble at all in finding proof for your beliefs. Being right is the booby prize in life.