What's the exact meaning of "where are you from?"

[japanjapan]

----Where are you from?
----I am from Chicago.

Sometimes,
----Where do you come from?
----I come from Chicago.

such dialogues are very common in the English text books, but the more i think over it, the more i am puzzled. What's the exact meaning of it?

I am from Chicago?
does it mean I was born in Chicago?

If one Japanese went to America and stayed in Chicago one week for business, and then he went to New York, can he say to his American business partner in New York " I am from Chinago?"

If one American was born in New York and for the last five years he has been living in Chicago, and now he is in Washington, should he say " I am from New York? or " I am from Chicago"?

If one Japanese has stayed in America for five years, and now he is in Japan, and he is in one university teaching English, can he introduce himself to his students like this: " I am from America."?

I am looking forward to your help, thanks.

[Tdol]

1 No, a Japanese visitng America would say that they're from Japan, even if they're in their second town.
2 When \people have moved around, they often say 'originally from New York, but now...'
3 Again, it would probably make sense to use the 'originally' idea.