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.
There was this girl who always had her headphones on. One day, she sat by the window. She took a deep breath in, and the music in her headphones seemed to amplify. It was a beautiful melody. As she breathed out, she closed her eyes. In her mind, she was in a meadow, the music creating the scene. With each inhale, she felt more alive, and with each exhale, she drifted further into the story the music was telling.