Day 1: I agree that it is very busy. Can you leave earlier in the morning? Eating lunch in Kilkenny is better than nothing but there are a few things to see and do, and lots of cute little shops, if that tickles your fancy. I'd plan for a few hours at ROC. There is also a great castle in Cahir to see but you won't have time unless you overnight in that area.
Day 2: I don't know anything about Kinsale so not much help here.
Day 3: Muckross House was fantastic, we loved it. You can walk to the Torc Waterfall through some beautiful scenery at the Muckross House estate. Definitely recommend it if you are able-bodied, it was gorgeous. If you want to hire a horse and buggy back to the House, I recommend that you reserve it when you first walk up to the park for the Waterfall. After we saw the waterfall, we wanted to ride a buggy back, but the wait was way too long as all of the buggies had already been reserved. You can probably see Ross Castle this day, too, if you want to fill your day with sight-seeing. It was my favorite castle (beating ROC and Cahir) and I'd highly recommend it as well.
Don't underestimate the drive time between Kenmare and Killarney. It's part of the ROK and very windy/twisty and takes a good 30-40 minutes, for us as least, to drive. There were also some beautiful scenic stops to enjoy along the way.
Day 4: This will be a very busy day, which we did in the reverse that you will be doing. There are LOTS of fantastic stops all along the ROK -- plan for a full day. We saw two ring forts that were both very different and very awesome. There was also a castle in ruins that was incredible. We loved the ROK and didn't run into troubles with the tour buses.
Day 5: I see in your amended itinerary that you are giving yourself a full day for the Slea Head Drive -- that is good and you will enjoy it. Again, tons of things to see and do just like the ROK. We loved stopping and hiking at different points along the rugged coastline. Stop for a snack in a pub along the way...one of my favorite memories were these older Irish gents gambling on horse races, yelling in a mix of English and Gaelic, at a small pub on the drive. We downloaded an app that gave audio highlights for each point along the Slea Head Drive -- great commentary and history. We just brought an auxilliary cable and plugged our phone into the rental car and listened from the car speakers as we drove.
Day 6: Depending on your interests, you may or may not wish you have more time at the Cliffs of Moher. In retrospect, my husband and I could have spent a half day there hiking along the cliffs but only had planned for a couple of hours, which I regret. If you are outdoors-y, I'd rethink how much time you spend. We loved the town of Doolin and heard great Irish Trad there. I see you are considering the Burren as well. I would suggest you consider staying this night in Doolin and see the Burren in the morning before heading to Galway on Day 7. We took a walking tour with John Connolly in the Burren and it was another highlight of our trip. There are also other interesting things to see in the Burren area like Poulnabrone Dolmen and Corcomroe Abbey.
Day 7: My suggestion is to see the Burren in the morning and drive to Galway for the afternoon and spend the night.
When I researched our trip, we were also interested in Connemara. The general consensus I received from other travelers is that it is a big, beautiful area worth a few days on its own.
Hope this helps!