Passport
technically none but if travelling by air the airlines demand a passport
If you are an Irish or British citizen photographic ID will do, including a driving license. As a general rule, always use a passport for travelling.
If your travelling from the U.K. then you don't need a passport but some form of I.D. is reccommended. If your from Europe then you need a passport to get into Ireland. Outside of Europe then i think you need to apply for a visa and bring your passport.
Not if they're travelling from Northern Ireland, but from anywhere else he/she does.
No sorry
No
only if you are going to Northern Ireland, you need a passport to travel between England and Ireland.
NoYou will need a passport or identification depending on your citizenship.
The British passport is one that is recognized as used for the people of England.
No. There is a common travel agreement between Ireland and Britain. You will not need a passport at any time when travelling across the sea between Britain and Ireland. Neither do you need one when travelling in Ireland, from the south of the country to the North. There is no border on the island. There is open travel between the islands/countries of Ireland and Britain. Google 'Common Travel Area Britain Ireland' .
No. They are both in Ireland, so if you are in Cork legally, then going to Dublin does not require any additional documentation. You may have needed a passport to get to Ireland in the first place. If so, then keep it with you when travelling around Ireland.