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.
It could be other elements from Japanese folklore. There are many supernatural beings and concepts in Japanese mythology that might have influenced his creation.
The scene of Sukuna's death in the manga is a climactic moment. It's filled with action and drama, as various powers and tactics are employed to bring him down. The build-up to this point is full of tension.
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, in some fanfics, Ichigo's true power might be depicted as an unrestrained force. It could break free from all the limitations he had in the original story. For instance, his reiatsu could become so intense that it can change the environment around him just by being released.