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.
Not unless you renounce your Canadian citizenship voluntarily.
NoSee US Citizenship and Moving Abroad.http://www.richw.org/dualcit/faq.html
You never lose US citizenship unless you either renounce it voluntarily or by serving in the army of a country that is in war with the US.
You'll lose everything you may have as a US citizen.
Generally, only if you revoke it in writing at a US embassy, outside the US.
He will become a dual citizen of the uK and the US.
No.
(in the US) unless you were native-born - TREASON.
Spain has dual citizenship agreement ONLY with Spanish countries of South America, Portugal and Philippines. Other countries have to renounce their citizenship if they can and then become a Spanish citizen- in your case the US allows you to renounce: so you must.
US and UK allow Dual citizenship. A person can be a US citizen and a citizen of UK if he/she desires to. But if a person applies to get naturalized as a citizen of UK when he/she is already a US citizen, then it will lead to losing US citizenship.So a person can have US & UK citizenship as long he/she is not a naturalized citizen of UK.
Never.
Yes. If one takes up citizenship in another country, then the US will consider that person to no longer be a citizen. There are circumstances where you can hold dual citizenship if you were born of a US parent in another country and vice versa. Many Canadians and US citizens are dual.