One of the best Jay Garrick stories is his origin story. It shows how he became the Flash and his discovery of his super - speed abilities. It's a classic tale that sets the foundation for his character.
Jay Garrick's age varies depending on different comic storylines. But typically, he's depicted as an older hero with an age that's not precisely defined.
Barry Allen's death in the comics is a complex situation. Sometimes he does die, but often there are plot twists and resurrections as part of the ongoing comic narrative. It all depends on the creative direction of the writers and the demands of the story at that time.