The number of chapters in Vinland Saga manga varies over time. Currently, it's in the hundreds, but for the most accurate and up-to-date count, you'd need to check reliable manga sources or fan communities.
Yes, Vinland Saga is based on some historical elements. It draws inspiration from the Viking Age and the Norse exploration. However, it also contains fictional elements for the sake of storytelling, like the personal adventures and relationships of the characters. But the backdrop of Vikings sailing, their culture, and the idea of a land like Vinland are rooted in historical research.