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.
The Last Lecture was a novel by Somerset Maugham. It was set in the 19th century British society and revealed the social class division and the gap between the rich and the poor through a young man. The novel reflected the complexity and contradiction of human nature with profound thoughts, real characters and delicate descriptions. It was praised as one of Maugham's representative works.