I actually am having the same optical sensor problem with my Kickr and should have a replacement soon. Did you have difficulties with the Kickr in ERG mode too? Mine would constantly drop the power readings from the Kickr. I could swear this was making the ERG workouts incredibly difficult; it feels as if the resistance is way above the resistance reading that I have set on the Kickr. However, it could just be my mind during the intervals... Interested to see what your experience was on this one.
To be honest, I couldn't get the unit to work properly enough to test it in any mode. The resistance would randomly go to level 9 (which really is not fun unless you are expecting it), and the speed would never go above 10mph at a normal cadence. So it was really just not fun to use in any mode. With the fix, however, that has all changed and I'm loving it.
Regarding the skewer issue, I simply replaced it with an old mavic skewer I had sitting around, and the problem was fixed. The skewer itself is a pretty simple device - an end nut and spring on the cassette end, and a beveled washer and spring at the QR end. I can't imagine I had it installed improperly. The skewer I replaced it with is infinitely easier to crank down, so I'm happy with that. Not sure why the stock skewer didn't work for me, but I haven't given it a second thought after the fix.