1) The murderer/kidnapper is clearly the teacher, they couldn't have made it any more obvious other than freaking putting a sign on him saying (I am serial murder)
2) The man in this episode ,aka the guy who killed fujinuma's mom was talking to the manager outside the shop, is the teacher in the future, and also the guy who set the house airi was in on fire.
4) Kayo ends up being saved, and is finally shown when they are both 29
5) Kenya is going to play a big role in the near future, not sure how, but he is going to help somewhere along.
6) I also think Yuuki is going to help fujinuma sometime soon.