Yuto is a very powerful exorcist with unique abilities. However, Seigen also has his own strengths. If they were to battle, it would be a close fight. Yuto's speed and agility might give him an edge, but Seigen's experience could counter that. In the end, it's hard to say who would win as it could depend on the situation and their mental states during the fight.
Yuma and Tori could be characters from a small - scale, indie story that has a dedicated but not widely - known fan base. The fanfiction allows fans to expand on their relationship, imagining their married life in ways that the original story might not have delved into deeply, perhaps adding more depth to their characters and their connection.
Yuto Ijika's death in the manga is quite complex. It could be related to a major battle or a twist in the plot. But to know for sure, you'd have to read through the relevant sections carefully.
3:10 to Yuma is purely fictional. It was created for entertainment purposes and doesn't draw from real-life events. The plot and characters were made up by the filmmakers.