I don't have enough information to determine who Jolene is in this story. She could be an ordinary person, a public figure, or someone known only within a specific community.
Not likely to be completely true. Maybe it has some roots in reality, but it's likely a combination of real and made-up elements to create a compelling narrative.
It's hard to say for sure. Some songs are inspired by real events, but might have fictional elements added. So, it's possible Jolene has some basis in truth, but it could also be mostly made up.