Easkey is actually the best thing of the year. I'm going to say something controversial here: It may even be better than Kerry. nobody should miss it for any reason, including the alpes.
some tips:
bring a folding camping chair or something. there's a lot of sitting and nowhere to sit.
it's freezing at night but sweltering when you wake up. pack clothes that will keep you warm in a sleeping bag, but that can be pulled off in your sleep with one hand with a hangover when it's 30C in your tent at 10am.
you're not allowed go up the castle until it's dark, and then you have to be drunk and can't use any light including the glare of your phone. sorry, them's the rules.
bring a torch.
bring plenty of fleeces, hats, etc. you will be up late, outside, and it will be cold.
if you smoke, bring plenty of cigarettes, the choice of brands in the village is limited.
likewise alcohol.
go to Inniscrone at least once. it's a lovely beach.
stay away from Easkey beach. it's awful.
be prepared to get very very little paddling done. I've only once seen surf there in the June bank holiday.