I'm not a mind reader, so I don't know whether he meant to say something different, but that is the gist of what he said. I agree that he wasn't suggesting that Americans inject bleach or disinfectant (that's been mildly blown out of proportion as the story has been retold), but he was definitely asking if that was possible. Which isn't really any better.
No, not really - it's pretty clear, in context, that Trump has no idea what he's talking about and is just trying to sound smart or insightful on camera. Those are absolutely questions that a person with no knowledge of the topic would ask, but a sensible person would ask them privately. Generally, throwing out completely infeasible ideas as possible solutions just makes you look like an idiot - which is why you ask the experts if they're possible first; before you speak to the entire country.