Any British citizen can enter the US on the Visa waiver program for 3 months as a tourist only--working is not allowed.
He is a British citizen residing in Monaco.
Yes, as long as the British citizen has not committed a crime or is otherwise ineligible for entry into the US.
William Henry Harrison was the last president not born a US citizen. He was born a British citizen when the 13 original colonies were British colonies.
If you are a US citizen living in the US, marrying a British citizen won't affect your Medicare benefits. That only becomes a problem if you move out of the country.
Yes they can live together
There is a distinct difference between a British Citizen and a British Subject. A British Citizen has free access to all parts of the UK. A British Subject may not. If you are a British Subject, you should check with the British Embassy in your country of residence. Incidentally, a British Citizen doesn't need a visa to visit the US but a British subject does.
No. The US Constitution requires the president to be a natural born citizen of the United States. It also requires a president to be at least 35 years old and 14 years a resident of this country. So not only could a British citizen not be president, but even a British citizen who gave up British citizenship and became a naturalized US citizen cannot be president.
Yes.
He is not a citizen of the US; however, he is a citizen of the UK and an honorary citizen of Italy.
None you have to be a American citizen to be President.
Yes, the British citizen comes over on visa waiver. You can get married. If you both plan to then go to the UK straight after, you will then need to apply for a spouse visa for the US citzen at the UK/British Embassy in the US. This will allow the US spouse to come to the UK and also work straightaway.