Sure did. Luffy overcame many challenges and ultimately emerged victorious against Kaido. It was a long and hard-fought struggle that showcased Luffy's growth and determination.
Luffy beats Kaido by unlocking new powers and exploiting Kaido's weaknesses. He also gains support from his allies and uses teamwork to his advantage. The battle is intense and filled with unexpected twists.
I don't have enough context to determine exactly who 'garp' is. It could be a newly created character by the fanfic writer, or it might be a character from a relatively unknown story that is being incorporated into the 'ace fanfic'.
Yes, there might be. The world of fanfiction is vast, and with the popularity of both Naruto and Kaido from different fictional universes, it's not unlikely that someone has created a crossover fanfiction where Naruto has some sort of connection to Kaido. You can search on popular fanfiction websites to find out.