Counts as fiction. The fact that it is historical fiction just means that it is set in a time period that existed vs. other forms of fiction such as fantasy or scifi that exist in invented worlds.
Historical Fiction is fiction based on real people and/or events, the only criteria being that the story is set sometime in the past. Some experts go so far as to say it has to be set in a time...
No. Realistic fiction indicates that the book is something that COULD happen, not that did happen. If there aren't talking animals or magic spells in it, for example, and it's a story about a kid...
A fiction library is when there is only fiction books, (stories that are made up) and non fiction libraries is when there is only non fiction books ( stories that are true)