As far as car-rental insurance, american credit cards (such as AMEX) don't cover rental cars in most "I" countries (Ireland, Italy, and Israel) due to added liability, so buy the loss-damage waiver offered by the car company.
Thanks SIUdude! I will do it. As much as I cringe my teeth in buying extra rental insurnace... I will do it, to have peace of mind.
By the way? Are the license plates different in Ireland (Southern part) than they are in Northern Ireland. The only reason I ask is because someone told me that rental insurance (from a car rented in DUB) will not be covered in N. Ireland-- and actually advised to stay out of Northern Ireland.