The problem (or one anyway) with the parkway one is that the Dublin road incoming comes straight onto it. Most roundabouts make you slow down and turn to the left. So cars hit this at 45 - 50mph which makes it very hard to judge trying to get onto it and disastrous consequences if you misjudge.
My recollection of the rules (or the ones I use!):
1st exit (turning left), signal left, get into the left lane on approach.
2nd exit (going stright on), left lane on approach, no signal on entry, signal left as you pass the 1st exit. On some roundabout where's there a big queue going left I think its acceptable to use the right hand lane on approach.
3rd exit (turning right), right lane on approach, signal right, after you've passed the first exit try to manouvre yourself into the left lane, you might have to wait until you pass the 2nd exit. Once you've passed the 2nd exit signal left, sometimes there are 2 lanes on the exit road off which makes things easier but obviously be careful when these merge (as do tend to within about 10 yards).
If things go against you then dont panic and whatever you do dont swerve because you're about to miss the exit. Do a lap of the roundabout on the inside lane & try again. BUT too many laps of the inside lane makes you dizzy !!!