1. Depends on who ISU loses to. 10-2 ISU in general is actually worse for BYU than 11-1 ISU. 12-0 and 9-3 or worse ISU give BYU the best chances. See the first table in
https://www.cougarboard.com/board/message.html?id=34023743
2. In general, I agree; this is in the last table of the OP
3. That makes sense to me. The other possibility is BYU goes undefeated, KSU wins out, and ISU finishes 11-1 (lost to KSU)
4. This is the second scenario in the second-to-last table of the OP, and yes, it's almost certainly KSU-ISU in the CCG in that situation