Yes, it is. In the original Naruto story, Kushina is Naruto's mother and their relationship is based on love and protection. The idea of her wanting Naruto's body goes against this fundamental relationship and is very disturbing as it implies a perversion of the mother - son bond.
In such a fanfiction, it could be a really dark and twisted plot. Maybe Kushina was somehow resurrected in an abnormal state and has some wrong perception that Naruto's body can help her achieve a certain goal, like getting revenge on those who once wronged her. But this goes against her character in the original Naruto series as Kushina is a loving mother figure.
Fanfiction often shows Kushina's influence through Naruto's values. Since Kushina was known for her strong will, Naruto might inherit that and show even more determination in tough situations. For example, when facing a powerful enemy, he might draw on that inner strength from his mother.
Naruto would become more confident in his abilities. With Kushina's training, he would have a better understanding of his Uzumaki heritage and the power that comes with it. This new - found confidence would show in his battles and his interactions with others.
One consequence could be Naruto's emotional breakdown. Since Kushina is his mother, her betrayal would be a huge blow to him psychologically. He might start to doubt himself and his place in the world.
Yes, there are many. Some fanfictions focus on the warm family moments, like Naruto's father Minato being excited and taking care of Kushina during her pregnancy. They might show how the village is also preparing for the arrival of the new baby, with friends and neighbors being supportive.
The plot could be that Kushina wants Naruto to reunite with his father. She could use her spiritual connection to Naruto to plant the idea in his mind. Naruto then embarks on a journey to find out more about his father, Minato. Along the way, he discovers secrets about the past, including how his parents really met and fell in love. This could also lead to him unlocking new powers related to his family lineage.
Perhaps Naruto finds a way to travel back in time and prevent Kushina's death in the first place. He could use his Sage Mode or some other special ability to manipulate time. And then, by changing the past, he effectively'revives' her in the present. In the Naruto universe, there are all kinds of crazy powers, so time - travel isn't completely out of the question.
In some fanfictions, Kushina was sealed into Naruto through a complex jutsu. It might be a modified version of the sealing jutsu used to seal the Nine - Tails. The process could involve special incantations and chakra manipulations.
One common plot is Kushina finding Naruto in a different time or dimension. For example, she might end up in the future where Naruto has grown up and she gets to see the kind of person he has become. It's an emotional and interesting concept as she gets to witness all his achievements and the challenges he has overcome.