Inosuke doesn't become a Hashira in the manga. The story progresses with him having other significant experiences and achievements instead of achieving that specific position.
It's hard to give an exact number. Different story arcs and battles led to the deaths of multiple hashira. Some died heroically, while others met their fate in unexpected ways. The count changes as the manga progresses.
Definitely not. Genya remains outside the ranks of Hashira throughout the manga. This is because of a combination of factors such as his skills, experiences, and the overall direction of the story.
One way to develop Baal's character is through his relationships. With all the time in the world, he can form deep and complex relationships. For instance, he might fall in love with someone from a different culture. Through this relationship, he learns about empathy, compromise, and self - sacrifice. He also has to deal with the challenges that come with loving someone in a world where time is both a luxury and a burden. His character could grow from being self - centered to being more community - oriented as he realizes the importance of the people around him through these relationships.
The fate of that city could have been varied. Maybe it was abandoned by its supposed deity and left to decline. Or perhaps it was destroyed by a more powerful force as a result of its idolatry.