I'm not sure specifically as there could be many different stories within this light novel. It might be about a magical revolution, perhaps involving characters with special magical powers fighting for change in a fantastical world.
Some online manga libraries like Viz Media or Comixology might have Dragon Ball Kakumei manga. However, it might require a subscription or purchase to access.
Well, Vegeta would be a likely character. He might be initially suspicious of the female Goku. Maybe he thinks she's a threat or just can't believe there's another Goku - like being. He could be there to add some comical moments as he tries to understand the situation.
In general, it's a bit of a toss-up. The strength of Manga Goku and Anime Goku can vary depending on the specific arcs and battles. Sometimes, it might seem like one is stronger in a particular situation, but that could change in another.
In other fanfictions, they could be rivals. Goku is always looking for a strong opponent, and Sailor Moon's unique powers could make her an interesting rival. They might have battles where they test each other's limits, but also learn to respect each other in the process. They both have strong beliefs in protecting their worlds and those they love, so even as rivals, they could end up on the same side when a greater threat emerges.