In English, there is an idiom, "Are we clear?" or "Is that clear?" to indicate that the listener has just received a correction or imperative from the speaker (usually over some kind of protest - the implication is that the listener misunderstood the speaker the first time instead of wilfully disobeying.) Is klar used in a similar way in Norwegian?
I disagree "Are you clear?" does make sense in English and I would use it!! Either to make sure someone was a sufficient distance from something, or to check understanding. I appreciate that perhaps a better Norwegian translation of "Are you clear" could be "du forstår?" rather than this sentence. That's my thoughts anyway! :)
Forstår du* verb should be first when posing a question.
Neither of your examples would translate to 'Er du klar?' afaik, although I'm not sure what would be common to say so make sure someone was at a sufficient distance from something.
"Er du klar" does not mean "Forstår du", it just asks whether or not a person is ready for something. The only way it could translate to "Are you clear" was if you were asking if about the transparency of a person, and even then 'klar' would be a weird choice of word.