Regarding Cha Shou Xun's death in the anime:
Here is a more in depth post about it.
Link: https://shojocorner.wordpress.com/2012/06/30/the-master-of-seduction-sakujun-sa/
During their travels to Kinka, in every city they stopped at Shurei bought all of the gan lu tea she could find so that way her comrades could follow her trail without her making her identity known. When Sakujun asks Shurei to make him some gan lu tea, she tells him that she’s saving it for the people who are important to her. She refuses to serve it to him, making him jealous that there are people who are more important to her than he is. Near the end of the first season, Sakujun decides to place a wager with himself: he poisons hot water and puts the antidote in the gan lu tea. He tells Shurei that if she doesn’t serve him gan lu tea he’ll die, but instead she chooses to serve him the water. Later on, Shurei finds Sakujun slumped under a tree, bleeding from his mouth. As he’s dying, he is pleased by the thought that Shurei will live with the guilt of knowing that she was responsible for his death: because then she’ll never forget him. However, as his eyes are closing, Sakujun says that he wishes he could have listened to Shurei play her ehru more, which shows that despite his frozen heart, some part of him really did genuinely love Shurei – or perhaps it was obsession. When Shurei runs to find him help, Sakujun’s body mysteriously disappear.
I hope they are going to follow this in the series but I am 50/50 that they'll do so because of the reuters about him jumping to his death after being rejected by the FL. But maybe it will be changed since they're still shooting the series.