where all the black people at?

I prefer "mixed", because I'm not bi-racial.

As far as I know (basing this on my Mexican sister in law) the correct and appropriate thing to call people from Mexico is "Mexican". Because they are. It's kind of rude to call, say, a Chilean or a USAsian "Mexican" though, so if you don't know, "Hispanic" is correct.

I think prefacing little-i indian with "American" is fine for clarity. Personally. But I'm not in charge.

African-American, IMO, sounds stupid unless you're talking about a naturalized citizen, in which case I think it would make more sense to refer to their actual country of origin... but if you're just talking about their appearance, I personally think "black" is fine.

My new semi-boyfriend is of Irish descent, and the sense of Irish ethnicity is still very strong in his family and community, so I suppose in a sense he's Irish-American... but it only makes sense to call him that in a specific context, when it has relevance. Otherwise, if I'm describing his appearance, he's white.