1. I've played Inverse Inspection, and there's a chapter about generals. When Yu Jian got the general's signature, he was obviously very happy, and you see, there is a statue of the general in Yu Jian's office. There are indications that Yu Jian is a fan of this general. As for why we should help Cheng Butang, it is because they used to be good friends, and he is a person who pursues truth, which is also mentioned in the reversal test.
2. It refers to the 7-year-old Futang who used perjury without knowing it, and was finally deprived of his lawyer's qualification.
3. Number