Kimimaro wins very high diff.
-His bones have already stopped Chakra empowered swords. That was Edo which has oft been suggested to lessen durability to an extent, given the user still is not full power. CM2 makes them impenetrable.
-Mifune lacks counters to Kimimaro's bone projectiles which would most definitely kill him in a CQC point blank hit.
-Mifune lacks any counters for Bone Forest. Not knowing what's about to occur could kill him, but Kimimaro occurring from behind him through one of the bones and making a direct hit would most definitely kill him (Mifune has no intel on Kimi popping up from any bone).
-In scenario 2, what Kurama cloak do you speak of? I don't recall any, but if you're talking about the one he gave out to the entire shinobi alliance, then he'd win since nothing Kimimaro does will end up hurting Mifune. On another note, Mifune would blitz Kimimaro with his immense speed and create enough momentum for his sword to pass through Kimimaro's defences (at least if he's not in CM2).