Hi Steve
You will easily get directions to these places which are close by the town of Killarney. The Black Valley is just on the Southern flank of The Gap of Dunloe. Another scenic route is to take the road to Kenmare which runs along by the side of the Lakes for quite a few miles.
The mountains in Kerry intercept the warm air of the Gulf Stream so the weather is notoriously changeable. However, if you hit it right it can be a spectacular landscape to see. Much of my youth was spent fishing in The Black Valley and my best images of it are in my head. Leaden days of torrential rain transformed suddenly by a burst of sunlight through the peaks lighting the rain clouds spilling down the hills - and a fly rod instead of a camera.
Hope you have a good trip.
Kevin