The judge with the white hair is Minatogawa. That is his elder name, his name when active in sumo was Daitetsu. He is Japanese.

There are no weight classes as I suspect you know. You can stand as far back from the white line as you want as long as you are in the circle, though most don't. Yes, you can slap in the face. It is called "haridashi". You are however, not allowed to pull on another's top knot or you are disqualified.
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We are what we repeatedly do - Aristotle