There will be a snowstorm tonight, so you need to pay attention to traffic safety. If you were reading a novel about traffic, there might be some traffic-related plots such as vehicle breakdowns, road closings, and so on. He could imagine some of these scenes according to the plot of the novel and try to understand and deal with them.
Well, Saitama All Fiction could potentially refer to a fan - created idea that emphasizes Saitama's ability to be above all the normal rules of the fictional One Punch Man universe. For example, his strength is so overwhelming that it's like he exists in a realm of his own, where the typical limitations of the story don't really apply to him. He can defeat any foe with just one punch, and this 'All Fiction' concept might be an attempt to explain how and why he's so powerful in such a ridiculous way.
Saitama's speed in the manga is incredibly fast. It's hard to put a specific number on it, but he can cover great distances in no time and react with lightning speed to any threat.