I'm not sure why you decided to fly into Dublin when it seems with your itinerary, that you want to see the west coast side of the island. It makes more sense to fly into and out of Shannon if you want the west coast and southwest, which is what this itinerary is.
However, since it seems your flights are already booked I recommend that you would only have time for two of these places. Certainly not the Dingle penninsula and the ROK. So pick one of those and save the other for next time.
Do you mean to say that you are landing at 2:55pm and then are planning on renting a car and driving? Have you thought you might be a bit tired from jet lag? Have you driven on the left before? That is a very long drive from Dublin on your arrival day. I would rethink this. If you have not been to Ireland before, perhaps see the east coast side of the island. You could do Northern Ireland and some of the great stops along the way like Newgrange.
Or you could do the southeast. Either way, those options are much less driving.
I have not stayed in Cork, so can't recommend anything there.
Dingle, Pax House B&B is awesome.
In Killarney, Killeen House on the outside of the town is marvelous!
Have fun and don't drive too much or you really miss out!
