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 memes in " Celebrating Years " referred to the memes that had some homonyms in the names of the characters in the play. For example, Fan Xian's name had a homonym of " making a nuisance," which meant that he was an annoying person. Fan Sizhe's name was a homonym for the famous brand " Versace ", implying that he was good at business. Fan Jian's name was a homonym for " cheap ", which matched his character. These jokes added some humor and interest to the characters in the play.