There is not enough information to answer -fly to the US from where?
Yes, as long as you are using the same company.
No you do not need a passport to travel from the us to puerto rico. you do need a visa.
Yes, US citizens need a visa to travel to London.
Yes, US citizens need a visa to travel to Ireland.
Yes, you do not need a passport to travel to the US Virgin Islands if you are a US citizen.
Yes, US citizens need a visa to travel to Kazakhstan.
Yes, US citizens need a visa to travel to Russia.
Yes, US citizens need a visa to travel to Uzbekistan.
You need at least 3 months left from the time that you depart for US. But many countries need at least 6 months left of passport validity for international travel.
As of June 1st, 2009, you need a passport to travel from Canada to the US.
To travel inside the US, you typically need a form of identification such as a driver's license or passport.
Yes, you need a valid passport to travel from the US to the Cayman Islands.