It is random. They give out random things. The harder the difficulty, the more items you get though. That's funny you say you didn't get threads because I noticed the same thing. I was playing normal and in comparison to easy, i didn't get as much threads. Might be just random though :p

Hans normal is the same thing as Hans easy mode. The only difference is you can't heal awayy the poison and karin is an extra stage separate from hanzi.

You use the same strategy you had with Shine to Karin as she only takes one damage per atk and heals self.