1. I wasn't sure if Kagome's arrows would do anything to Bankotsu since he is human, kinda
2. Kohaku said in the episode "It's not a place where humans with evil in their hearts can feel comfortable" but to me Kanna didn't really looked bothered by the barrier on the mountain
and to that effect if teh Priest is creating the barrier on the mountain and it purifies demons why is he(the priest) helping Bankotsu with the Dokko?