Were the girls hookers or not ???

I have to say yes. Both women were charged and arrested for accosting and soliciting six days apart in the following September after the killings, and both served six months probation. According to John Hersey's book about the Algiers Motel killing, they had a "protector" named Eli "Bubba" Carter. However, Julie Hysell (one of the women victimized) claimed she and Karen Malloy were following a R&B musical group, and were staying at the Algiers Motel because of the low rental fees: https://www.freep.com/story/entertainment/2017/08/04/survivor-detroit-movie-kathryn-bigelow-algiers-motel/532497001/

You can read the details of their arrests in the following link: https://tinyurl.com/y7omehl2

As per the movie the weren't. I ma not aware of the actual facts.

We see them discussing the possibility of offereing sexual in exchnage of money as they were broke at that instance. It also shown that one of them was not really comfortable with the idea. When asked by the police officers if their dad knew about their whereabouts they just stay quiet. They probably ran off temporarily and were pondering over making few quick bucks just to get by.