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.
These sounds seem to be used to create an atmosphere that is related to sexual undertones in the fanfic. However, this is not a good practice as it involves vulgarity. Fanfic should be more about creativity in positive and appropriate ways, like exploring different characters' relationships in a non - sexual way.
I don't have specific 'nuh ghost stories' on hand. But generally, ghost stories often involve spooky elements like haunted houses. Maybe in the 'nuh ghost stories' there are tales of ghosts lurking in old abandoned buildings at night, with strange noises and cold drafts.
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.