In such a fanfic, the real world's reaction would vary. Kids would probably be excited and see Naruto and his friends as heroes. However, adults would be more cautious. The media would go crazy, reporting on every move of these new arrivals. There would also be those who would try to profit from the situation, selling Naruto - related merchandise or offering tours to see the 'newcomers'.
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.