The Question and Answer section for The Chosen is a great resource to ask questions, find answers, and discuss the novel.
Reuben is from a less orthodox religious background and attends a more secular yeshiva. He really disapproves of Danny's father's, Reb Saunders, orthodox Jewish beliefs. It is ironic that Danny should actually become a rabbi.
Yes it is in chapter 13.
When Reuven returns to school, his friends treat him like a hero. Reuven does not like this and thinks they are being childish.