The Last of Us was not a comic originally. It was first developed as a video game, which gained significant popularity and later inspired other related media, but the comic came later.
The duration of the story in The Last of Us depends on several factors. If you rush through the main quests, it could be around 12 hours. But if you take your time, do side quests, and explore the environment thoroughly, it could stretch to 25 hours or more.
Well, it's quite important. This side story enriches the whole narrative. For example, it might show some events that were only hinted at in the main plot. It can also introduce new elements to the world - building of 'The Last of Us'. Maybe it reveals some secrets about the infected or the post - apocalyptic society from a different perspective, that of Ellie and her friend, which is really cool and makes the whole game world feel more complete.