We had to climb up some narrow, somewhat winding stairs. There was no other obvious entry but we did not ask.

Well you learn something new everyday..I had not heard of Uber before. I drove there myself. It is a short tour around the castle. It's lovely but I think getting the Luas or a bus would be cheaper.

Yes, we paid after the tour. I think it was about 4.50 euros per person. They do have a website and you can get more detailed info there.

Yes there is free off street parking available. If for any reason you cannot access the parking (if the gate is closed) you can park in the nearby Aldi supermarket carpark.

I agree that taking a bus is much easier and the bus stop is in front of the castle.

one or two hours would be enough to see it, it is well worth seeing though. and if you want food & drink try the Half Way House just across the road, have a look at the lovely old style bar there.

Hi, you can get a 18 or 151 Dublin Bus and then walk a short distance to the castle entrance. Just ask your driver where to get off. You could also get a taxi and ask to get out at Long Mile Road, Drimnagh. Thanks Drimnagh Castle