Sorry, I don't have the specific name of the author of the Ennead comic. Maybe you can look for it on popular comic forums or websites dedicated to comics.
Well, Kushina could initially be disappointed. But then she might see it as an opportunity to help Naruto find his true passion. She could start introducing him to different things, like maybe some traditional Uzumaki family skills that don't necessarily involve being a ninja in the typical sense. This way, Naruto could still have a sense of purpose and connection to his heritage.
Kushina would be extremely worried. She would rush to Naruto's side immediately and start using her medical knowledge or any available resources to help him get better.
She could also be amused in some cases. If the fanfiction has some really out - there but harmless ideas about Naruto, like him having a strange hobby that doesn't really change his fundamental good nature, Kushina might find it funny and just shake her head at the creativity of the fanfiction writer.
Naruto would probably be really confused at first. He's used to a loving mother figure, not a yandere one. He might try to talk to her and understand why she's acting so strangely.
Some villagers might be in shock. Kushina was an important figure in the village's history, being Naruto's mother. There would be those who would question Naruto's decision and lose faith in him. They might start to fear for their own safety, thinking that if someone like Kushina could be banished, they could be next.
Minato might be intrigued. He would be interested in seeing how the fans expand on Naruto's journey. Kushina would be delighted, seeing her son as the center of so many different tales.
Naruto might be extremely heartbroken. He has always looked up to his mother, and being disowned by her would be a huge blow. He could become withdrawn and start to question his own worth.