Observations based solely on a week of driving there c20 years ago so don't take my word for it - things may have changed:
On rural roads if there's enough room for two lanes of traffic in each direction then it's not unusual for everyone to drive on the centre-most lane by default and only move over to the edge if there's a faster vehicle behind, rather than driving in the leftmost lane by default and using the second lane only if overtaking. I think I recall believing this was because the edge-most lane was often badly cracked and full of potholes, so it may be that things are different now.
Caution - because of this default I very nearly had an accident when I didn't spot until the last second that a vehicle ahead of me was actually slowing down and stopping in the second lane in order to turn right (no central lane to filter right either)
I was a fairly inexperienced driver at the time, maybe it wouldn't have been a big deal if I had been more experienced but it shook me up a lot at the time as it was so unexpected.
Your car needs to display evidence that it is insurered and you need to have your license with you at all times.
If your satnav will warn you of locations of speed cameras it is illegal to have this function active.
There are crossroads which in the UK would be controlled with a mini-roundabout but in Ireland have none, you just need to imagine one - where the two roads crossing each other are the same level of priority and each of the 4 ways gives way to the right.