1. Man idk, I don't think it hurts anyone to ID as non-binary, as long as it ain't some weird tumblr gender like flowergender or w/e
2. My cis friend was given hormone blockers when she was nine because puberty was starting too quickly and nothing bad happened to her when she stopped taking them. if a kid taking them because they thought they were trans then realizes they're actually cis while they're taking them, they can just stop taking them and puberty continues normally. Surgeries should probably be done at 18, since they're very expensive and from what I've heard, painful.
3. Anorexia can be treated through therapy and medicine, and getting modifications/surgeries aren't needed. It's also not necessarily something you're born with. Gender dysphoria, on the other hand, can only be treated by transitioning, and it is something you're born with. Your mind is a different gender from your body.