I don't have enough information to say for sure. It could be fiction, or it could have roots in reality that have been adapted or exaggerated for a particular purpose.
A 'historia visual novel' could be about various things. It might be a story set in a historical context, with characters and plots that unfold in a way typical of visual novels. It could focus on a particular era, like the Renaissance or the Victorian age, and tell a fictional story with elements of that time's culture, society, and events.
I don't believe it's true. Most of the time, when a story has a name like that, it's made up to capture our interest and take us on a fictional journey rather than being rooted in reality.
It's hard to say for certain. Sometimes stories like 'La Esclava Blanca' combine real-life elements with fictional creations to make an engaging narrative. You'd have to do some research to know for sure.
Yes, there are quite a few. You can start by looking on fanfiction.net or Archive of Our Own. Some fanfictions might explore their relationship in an AU (alternate universe) setting, like a modern-day scenario where they meet and get married, while others could be more in line with the original story's themes and settings but with a different plot twist leading to their marriage.
There could be some, but it really depends on the market and the fan base. Since visual novels are a diverse genre, those with a historical focus might not always get the same level of mainstream attention. But in the communities dedicated to visual novels and historical fiction, there may be some well - known 'historia visual novel' titles that are highly regarded for their storytelling, art, and historical accuracy.