Dia dhuit! Hi!
Here the general site for Public transport/lift Sharing @ the Isle: https://getthere.ie/
You have verry good connections with the ExpressWay / Bus Eireann on the Rosslare Harbour Ternminal
A few connections have a Change @ Waterford (Travel Times ca. 3hrs > 4hrs)
National Bus company: https://www.expressway.ie/
Private Express bus operators (when you stay @ Cork): https://www.citylink.ie/routes
>>> Direct from the Airport & Pick up @ Dublin City (Border Liffey, Tara Station area) to Cork/Galway/Limerick/... Drop of only @ the return
Daytrips from Cork to Dublin/Galway possible (Almost same costs as the single fares)
Good vibes travel with GoBus on the Dublin-Galway route.