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.
Well, without more context, it's hard to say precisely. But generally, visual novels are a form of interactive storytelling. 'Subarashii hibi visual novel' may be about a series of amazing (subarashii) days (hibi) that the characters experience. It could include elements like romance, adventure, or mystery, and through the visual and textual elements of the novel, the player or reader gets to immerse themselves in this world of 'subarashii hibi'.
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.
In the manga, Sukuna does acquire all his fingers over the course of the story. This is a significant plot development that has major implications for the storyline and character dynamics.