Q: If I buy an iPod in the U.S. will it work here in Ireland, and what equipment do I need to get to make it work here?
A: Yes, you can buy an iPod in the U.S. and use it anywhere.
The only real issue with compatibility would be power adapter requirements, however the iPod does not include a power adapter, so you would need to purchase this separately anyway. You should therefore wait until you return home to purchase any additional accessories that use external power, as these will not necessarily be compatible with the European power systems.
Any other accessories, however, such as headphones and USB-based accessories are standard and will work anywhere.
The only other caveat is iTunes Gift Cards, in case you’re tempted to purchase one of these along with your iPod nano. iTunes Store Gift Cards only work for stores in the country where they were purchased, so if you buy an iTunes Gift Card in the U.S., you will need to set up an account on the U.S. iTunes Store, with a U.S.