In what order did these events happen? In other words, before you told her "yeah" in response to her question about whether you wanted "explicit photos" of her, did you know that she was a minor? Or did you not bother to ask "her" age until after "she" sent you the picture(s)?
No, they're not. Her parents can report what happened to the police, but only the county prosecutor can actually file charges against you.
Yes. Either you knowingly solicited "explicit" photos from a minor or you solicited "explicit" photos from a person whose age you didn't know.
Hint for the future: There are plenty of really explicit photos on the internet. You don't need to solicit them from persons unknown to you. By the way, unless you actually spoke with this person, you don't actually know if it was a female.

