Einstein visited the US on a number of occasions before moving to the US permanently in 1933. He applied for US citizenship in 1935 and remained in the US until his death in 1955.
If you're asking whether any US Presidents were constitutionally ineligible to hold office, the answer is no.
If you apply for citizenship in another country your US citizenship is automatically revoked. The US does not recognize dual citizenship. You revoke it in writing at a US embassy, outside the US.
Yes, The residents of US territories have US citizenship
Just like you would in America..you get a passport..pay for the trip and move there and get your citizenship or a type of green card like here
The US recognizes dual citizenship.
No. The US president MUST have US citizenship only.
True.
If you are born in the US you obtain US citizenship by birth. Another way to obtain citizenship is through the naturalization process by applying for US citizenship using Form N-400 if you are eligible.
Yes dual citizenship is allowed for US citizens.
Mark Zuckerberg did not renounce his US citizenship. He did, however, give up his US citizenship while acquiring citizenship in other countries to avoid double taxation on his assets.
US citizenship can only be renounced in writing at a US embassy (i.e. outside the U.S.). Be sure you have citizenship in another country before doing this.