This stuff needs some "research" !!
Hate to say it, but I think if born on US soil you have a "right to US Citizenship". Not that I agree.
I also think that if you are born on a airplane flying over US territory, the same applies.
At some point I think you have to "declare" (as for your High school friend) and may be entitled to dual citizenship.
I also recall military service requirements/issues that can complicate that decision.
Needs research !!
I am quite sure though, the requirement to be President of the United States is NOT Citizenship, but BEING BORN ON US SOIL, and thereby you are by definition eligible be a US Citizen as I under stand it.
Arnold Swartzenegger past Governor of California is a US Citizen, but he cannot run for President of the US as he was born in Austria.