It's quite possible. New characters could add new dynamics to the story. They might be allies or foes of the existing characters, bringing new plotlines.
There might be. Since it's a new addition to the Bleach franchise, it's likely that the author will introduce new characters to bring new dynamics to the story.
I don't know specifically. But usually in Bleach novels, new characters are introduced to bring fresh storylines. They could be new Soul Reapers, Hollows, or even something from a different realm in the Bleach universe.
A new character could be a rogue Soul Reaper. This character has his own set of beliefs about how the Soul Society should be run and is constantly causing trouble for the Gotei 13. He might have a unique power that allows him to manipulate souls in ways that others can't. His role would be to be a constant thorn in the side of the established order, forcing the main characters to question the Soul Society's rules.
It's possible that there could be a new Bleach manga in the future, but as of now, there's no concrete information or confirmation. Maybe if there's enough demand from fans or the creator has new ideas, it could happen.
Well, there's no definite information yet. Usually, it depends on the popularity and commercial viability. Sometimes, publishers might decide to bring out new content based on fan requests and potential sales.