Yes you do.
No. Passports are for international travel.
Yes. To enter the Dominican Republic you will need your passport. period.
No they don't need a passport. Adults only need a passport to enter foreign countries. Americans can travel freely between the U. S. states.
If you are a foreigner yes you need a passport as well as a travel visa to enter the country unless you are part of the ASEAN where you only need you passport.
Yes one would need a passport to travel to Barcelona as if one is going abroad on holiday one would need a passport to enter the country. If one lives in Spain the passport is not required.
No. The only time a passport is required is when you are leaving U.S. borders.
Yes, everyone needs a passport to enter the United Kingdom.
British subjects do not need a passport to enter Ireland if they are arriving directly from the United Kingdom, but you may need your passport for your airline, travel company etc and should check beforehand
Yes, especially when you need to travel by plane. If you do not have one then you should apply to get one so that you can travel in and out of France. For non-citizens then you also need a visa in order to enter.
If you are a United States citizen, you do not need a passport to travel from NY to California, as these are both part of the U.S. If you are not a United States citizen, you should have your passport from your home country with you whenever you travel in the U.S.
Yes, anytime you leave the country you do.