This is a well-disputed topic.
So, it all depends on what we call "emphasis". In fact, in both sentence the focus is "mit" - that's why it precedes the verb immediately. The new piece of information is going to relate to the question what, hence you could say it has to be emphasised.
And then there is another thing you were referring to as "emphasis". That's the topic. It's not new piece of information, it just sets up what the new piece of information will be about. With "Mit lát a bíró?", you don't set up a topic, you just go ahead for the detail that you really want to know. On the other hand, with "A bíró mit lát", you set up "a bíró" as topic.
Of course, this is a kind of "emphasis" as well. "Mit lát a bíró" suggests that it's kinda obvious that we are talking about the judge anyway while "A bíró mit lát" explicitly redirects the context to the judge, just in case it wasn't obvious. But still, it's not a new piece of information.
Ya, the progressive ("is ... -ing") is less commonly used for "to see" questions than the regular form ("does ... -ing"). "What is s/he seeing?" works as an exclamatory question, but as a regular everyday question, "What does s/he see?" would be more common. If intent is part of the equation, even better would be "What is s/he looking at?" (i.e., paying attention to, not just passively aware of visually).