>>>Ah, two things here. First, the lack of word for "what" instead of "what" in English, the first one asking for an adjective ("what door is this" - "a green one"), the latter one for definition ("what do we have here?", "a door"). I've seen this so many times...

If we wanted to know that we'd say "What colour door is this?"

If you're suddenly placed in front of a door, and told to enter, you may say "What door is this?" as in "is this the door to death, or riches", etc.

AND: I need to go into a hotel and fetch a packet. I say "Which room is it in?" or "what room ..." but the former is more grammatically correct. We're just lazy (like the "less people here than last night" abomination.
OR "Sweetsville - a nice place to live" (cf "... - a nice place in which to live")

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>>For the first, we would say "Which door is this?". The second case, yes, we would use 'what'.
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>Nope, "which" asks for a way to identify one among the many (just like the guy asked his unresponsive wife, "which dick is it to you today" (meaning "what's the matter"), and she said "fifth"). There is simply no such word in English. "What kind of" comes close, but it still asks for a noun, not an adjective. "How are you" is asking for an adverb - need equivalent word for adjective. Every other language I know has one (even, IIRC, the clumsy German "was für ein" does the job).
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>>>The second is that, in most Slavic languages, Hungarian, German, Italian (and who knows how many others), the question is not "what do they call you", it's "how do they call you", or even "how's your name", never a what.
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>>Yep. I never got over the fact that in French, one doesn't ask "How are you?", but instead, "How do you go?" , or, I suppose, "How are you going?", to which we, in English, would answer, "By bus."
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>In many languages, "how do you like it" begs for "I like it nicely"; "how are you?" - "I permanently am".