Yes, they do. I had the pleasure of being in Dingle (west coast of Ireland) last month and could easily hear native Irish Gaelic used in daily life and conversations. Maybe much less so in Dublin. If you go there, you'll see that most signs are bilingual. A number of Irish words replaced English words in English conversations when I was there, eg. uisce (water), bainne (milk), oiche mhaith (good night), suí sios (sit down) and so on. Alison.com offers a free basic online course: http://alison.com/subjects/72/Irish-Language-Skills

My understanding is that Gaelic is commonly used in many parts of Ireland, but that it's usage is on the decline. Increasingly, Gaelic is a second language and formal training in it among the young is decreasing in some areas. As it is likely that the average age of fluent Gaelic speakers will rise over time, you will have the most options by visiting the country sooner rather than waiting decades.