At all costs, try and avoid driving in the Republic of Ireland. It's not actually dangerous, just painfully unproductive.
- Don't be at-all surprised if nobody ever asks to see your passport, aircraft documentation, or anything else.
So true, you need plenty of time when you drive to anywhere except between the bigger cities. Roads signs sometimes seem to be works of fiction.
ATC is very relaxed and helpful. I once asked for FL120 in controlled airspace without a flight plan. No problem.
Pity about all the driving. A better option if you had been able to get there would have been Weston Airport. It's situated right beside the motorway to Galway. A much easier drive, two and a half hours roughly.
Waterford airport as you found, is very friendly. Galway not so. They also close at odd times and last year they closed early for some reason in spite of the fact that there were two solo students on the way, flight plans filed, forcing one into a fuel diversion and other getting a bit lost because of the unexpected diversion. Most Irish pilots avoid Galway if possible because of their attitude. Once I was getting fuel and the fueler tried to collect landing and parking fees off us at the same time as if we were trying to get away with something. Having said that I find ATC there quite helpful. It's more an airport management rip off mentality. I have certain similaropinions about Galway city in general too.