Qing Yuannian's password was Wu Zhu's name. In the movie, Fan Xian opened the box his mother had left for him and found a combination lock on it. After inserting the key and entering the password, Fan Xian successfully opened the box. There was a letter inside. Fan Xian needed to use the five-stroke input method to enter Wu Zhu's name to unlock the password.
Sukuna does die in the manga. The way it happens is quite dramatic and ties in with many other elements of the story, adding depth and tension to the overall narrative.
No. Ryomen Sukuna is a fictional character from Japanese mythology and modern manga/anime. He doesn't have a basis in a true historical event or person.
Nope. Ryomen Sukuna has no basis in reality. It's a product of the creative minds of the writers and illustrators who designed a captivating fictional character for the enjoyment of the audience.
In the manga, Sukuna doesn't possess all 20 fingers. There are specific story arcs and events where his finger count changes based on the plot developments.