The Question and Answer section for Thirteen Reasons Why is a great resource to ask questions, find answers, and discuss the novel.
This is really up to you. Different characters share various amounts of "blame" but, in the end, only Hannah is responsible for her actions.
Marcus wanted to coerce Hannah into fooling around with him.... he wanted to humiliate her.
I'm sorry, this is a short-answer literature forum designed for text specific questions. If you have a question about the novel, Thirteen Reasons Why, I would be happy to help. I have no information about the series based upon the novel.