I really like 'Sanegiyuu: The Unspoken Understanding'. It delves deep into the unspoken connection between Sanemi and Giyuu. The author does an amazing job of portraying their internal struggles and how they gradually come to understand each other better. There are some really touching moments in this fanfic that make it a must - read for sanegiyuu fans.
Social media platforms like Tumblr can also be a good source. There are many fans who post about their favorite sanegiyuu fanfics on there. You can search for relevant tags such as #sanegiyuu #fanfic and explore the posts to find some good reads.
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.