SPOILERS ALERT - regarding the ending...

... so are we to take it was Sharon Stone's character who alone murdered all those calendar girls? Or was she perhaps not acting alone on this? And if so, what was the deal with that guy in the van, why were the police after him?

And ultimately speaking, I understand that Sharon Stone's character had some sort of problems with her father, but why kill those other girls because of that, I didn't quite get it?

Thanks.