That's annoying. I think you should call a few companies and see what the going rate in your area is for a house your size.
I'd decide if I wanted a housekeeper at this time and even if she seems nice and like she wants to do you a favor, I would formalize a few things because this "Oh, I don't know" and "I'm here to help" is getting a little silly. Either she's a volunteer or an employee and you need to figure out which.
ETA: You need to steer this ship, no matter the common connection. YOU lay out the terms. If my housekeeper was 1.5 hours late I would not be inclined to have her come back, no matter if she went to my church or not. Since she's not being professional and you want to give her a chance, you need to figure out what YOU want and need and tell her - and if she doesn't like that then she can help someone else. Help is not helpful if it's not reliable or causes you issues.
FWIW, our lady (who we have used off and on since before DD was born) is paid about $25/hr or $100 per visit. It is not a huge house, but we do have 4 bedrooms and 3 bathrooms.