@Lita
we see this from the viewpoint of an eye witness. In episode 13, The Rain Master legend, an eyewitness who saw shopkeeper Zhong leaving his shop at night said Zhong left the shop in normal clothes, this person (the eye witness) was standing across the road at his stall when suddenly a gust of wind blew his umbrella, when he looked back shopkeeper Zhong had become a Birdman (probably Zhong has adorned his costume then) started running and flew away (the camera during that part of narration shows a bit obscured image due to rain drops on the lense, so presumably the eyewitness was not able to see clearly in the rain at a distance and his mind played a trick on him. People are very susceptible to thoughts of supernatural in certain scenario).
In Red Pavilion case,
Q. why did he kill himself to protect her? So as not to infect her?
A. Yes, he suffered from a terminal illness like his father. Also because people bitten by sand fleas feel endless pain, their body begins to fester. I presume Li Tao must be in extreme pain suffering from an incurable disease that he feared might infect her. So in my opinion he committed suicide.
Q. Why did she try to find his will? Shouldn't her name in the will is more likely to make her a suspect?
A. I presume Qiuyue wanted a better future for herself. She had rejected Li Tao proposal earlier because she believed he would just make her a concubine and was not sincere.. Even though she loved him, when she saw he was already dead and had told her some time back about making a will in her favour. She had already lost her lover but she still had hope of securing a better life for herself in future IF HE HAD Actually made a will. So she was searching for a will.
If the will was actually found, proby she would he the prime suspect... But at that moment her thoughts were more focused on her future than anything else...
Q. Where's the missing will?
Judge Di in episode 18, deduced that due to the open window, a gust of wind may have blown away the will that might have been on Li Tao's table after he had finished writing it.
Q Why was the ink still wet after he died?
Probably he had just finished writing the will before he took his life so the ink was wet, indicating ink had been used recently for writing something just before his death.