yes
Yes they do.
No, unless they fly in to Scotland from outside the UK.British and Irish citizens (but not British "nationals" from Hong Kong or other places overseas) can fly within the British Isles with a photocard driving licence.Other EU citizens can use their national ID card.Everyone else still needs a passport.
Passports are needed for most citizens to enter countries around the world. Irish nationals who are visiting Jamaica do not need a visa, but do need a passport to enter the country. Grand Cayman requires a passport and a visa if the trip is going to be beyond 10 days and its for business or 60 if you are on vacation. Mexico requires a passport and no visa if the visit is less then 180 days. Haiti requires a passport but no visa if trip is less then three months.
That will depend on what country you are from. British and Irish citizens don't need one to enter Ireland. Citizens of other countries would need one, and some may even need a visa to get to Ireland.
Yes, it is ok. But to avoid possible questioning at the airports, apply for a British passport for her and, if you are Irish too, also get an Irish passport for yourself.When you go abroad, take both with you, but for departure from other countries, use the one passport you used to enter them.
Citizens from Nigeria need a visa to enter in Romania.
No. American citizens don't require a visa to enter Mexico. All you need is your passport.
Valid passport with visa; or identification card for EU countries citizens.
countries that are visa free to kenyan citizens.
You can certainly apply for a passport - all US citizens are entitled to one - the question becomes will the country you wish to travel to allow you to enter?
They don't. European citizens can enter and leave Mexico without additional requirements besides their passport.
Just a valid US Passport. No visa is need to enter El Salvador for US Citizens for pleasure purposes.