We won't have a formal rehearsal dinner (they're not customary in Ireland) but we will have a "welcome" gathering at Ryan's Bar in Cobh on Thursday at 6 pm.
We've noticed some differences between what's customary in Ireland vs the US. In Ireland, guests bring cash in an envelope to the reception to be dropped into a mailbox. Americans usually buy gifts sent to the couple's home in advance of the wedding. Just do whatever feels right.