The only thing I would add is to talk to him about what your needs are. It sounds like you have thought of a few. Privacy is important to you for one.
You don't have to be like her, but taking her as she is might be helpful. It could be that she wants it all to work out so much that she over talked and made herself overly vulnerable when you first met. I would think that would calm down with time. All of it will likely calm with time and as they all get to know you. What you need to think about is what you will do with YOUR time or whether or not you really want a relationship like this.
Oh, ya, and you don't have to date or be intimate with anyone you are not attracted to. That is not a poly rule