There are so many pieces to your story -- and so many things to do.
For starters, I would report the rape, both to the school administrators, the board of elections, superintendent, etc.. and also to the police. If your friend doens't want to for her own sake, at least for the sake of others who are equally vulnerable. I'm not sure how much time has passed, but obviously the sooner the better. Reporting to the police is important in order to build a case -- even if she decides not to pursue it.
As for the pregnancy, she needs to decide what she wants to do -- sounds like she really doesn't want to have the child of the man who raped her -- certainly not a wanted pregnancy. I would contact a local planned parenthood about having an abortion. Good that you are being a good friend.