Halloween in Ireland? Of course. Halloween trick or treating (though I think it might have been known simply as throwing cabbages at doors) originated in Ireland, as did the carving of jack o'lanterns - turnips were used until the Irish began emigrating to the US where pumpkins were more plentiful. Your question: do they party in Ireland on Halloween? You bet.
One of the biggest Irish Halloween parties is in Derry (Londonderry) - music, fireworks, parades - bring on the Banks of the Foyle Hallowe'en Carnival! This cool walled city has plenty to offer besides Irish Halloween traditions like Colcannon (Irish Halloween dinner of boiled potatoes, kale and raw onions) and hearty ale - though there is a lot behind the old saying (yeah, that one - eat, drink and be merry).
Budget Derry Travel Guide
The Walls of Derry
Ireland Train Pass Info