As of the current manga chapters, Sanemi is still alive. His character has gone through many challenges but has managed to survive. The plot continues to unfold with him as an important part.
Inosuke survives throughout the manga. The story doesn't have his death as part of the plot. His character remains active and plays a significant role until the end.
Well, Inosuke's origin story is quite interesting. He was found in the mountains as a baby and was raised by a family of boars. This led to his rather unorthodox and savage behavior. He didn't have any proper human upbringing which is why he often acts on his instincts. For example, he is very aggressive in battles and doesn't really follow the normal social norms that other characters do. His origin also influenced his unique fighting style which is very much based on brute force and his animal - like agility.
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.
Inosuke doesn't die. The author keeps him alive to continue his adventures and growth. His character's resilience and fighting skills enable him to avoid death.