As for Liev, if I remember right, Liev loved working on CSI, but it was too fast paced for him. And, Naomi Watt had just given birth (or was about to) to their first son... I think that was a factor.
So far, I'm not minding Ray this season. I wish though during the three way cross-over more members of each team could have interacted.
Oh, did I miss something or are there details about the Rascall Flatts episode? Are they going to be themselves? Will it be like when John Meyer was on? I'm just curious.