I don't think it's a straightforward true story. Usually, such shows take liberties and combine various elements to make it more captivating. Maybe there are loose connections to reality, but it's not a pure retelling of actual events.
Infinite novels usually referred to the combination of real and fictional elements to construct an infinite loop of story worlds. In this world, the protagonists often faced various challenges and dangers while constantly searching for their identity and purpose. Infinite novels often involved science fiction, fantasy, martial arts, and other elements. Sometimes, they would also add some psychology, philosophy, and other fields of content. Their unique feature was the ups and downs of the plot and the deep character portrayals, which usually involved some deep thinking and discussion of human nature.
Definitely. The Infinity Gauntlet comics came out earlier and laid the foundation for the concepts and characters seen in Infinity War. There are some differences, but the comics serve as a precursor.
Avengers Infinity War is largely based on the Infinity Gauntlet comic. Many key elements and plot points are drawn from it, but there are also some creative adaptations and additions to make it work for the cinematic universe.
Sure, Skate the Infinity has a manga adaptation. It expands on the story and characters from the original source. The art style is also quite appealing.