Well, it's not a straightforward yes. Some DC movies are direct adaptations of comic stories, but others take elements from multiple comics or even deviate significantly to offer a fresh take on the DC universe.
Not all DC Comics novels are suitable for all ages. Some, like 'The Dark Knight Returns', have a darker and more violent tone that might not be appropriate for very young readers. However, there are also many that are family - friendly, like some of the Superman stories.
Well, 'dc gamer fanfic' could be about fans creating fictional stories related to DC (Detective Comics) in the context of gaming. Maybe it involves creating new adventures for DC characters within a game - like a Batman game where fans write about new levels or challenges. It could also be about crossovers, for example, DC characters meeting characters from other games in a fan - made story.
Most DC Comics novels are suitable for a wide range of ages. However, some of the darker and more complex ones, like 'The Dark Knight Returns' or 'Arkham Asylum: A Serious House on Serious Earth', might be a bit intense for very young readers. But in general, there are many that are family - friendly and can be enjoyed by kids as well as adults.
I'm not entirely sure specifically what 'dc online story' is without more context. It could be an online story related to DC Comics, perhaps fan - created stories set in the DC universe.