It is only appealable in the case your hypothetical scenario of Dick Cheney dismissing his own case materializes. Otherwise, if the trial proceeds as intended, and reaches a conclusion (regardless of the verdict), it cannot be appealed.
I don’t know. You could be right, of course, but with no appellate machinery in place, I can’t see it being created ex nihilo. But like I said, it’s the Dem’s problem, innit?