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.
It's not easy to say who has the upper hand. Archer has the advantage of experience and a more complete set of skills. But Shirou has his own tenacity and the ability to surprise. In different situations during the battle, either of them could seem to be in control for a while.
Well, it varies. In some stories, the Daleks' sheer power and ruthlessness give them the edge. But in others, human ingenuity, courage, and unexpected alliances can tip the scales in their favor.