Originally Posted by bivio
Try looking at her as your casual sex partner. Meaning you have the relationship of a couple but it's nothing serious. See if the relationship between you works out but just be prepared for heart ache.
This was my impression as well.
I don't believe there's any harm in being in a relationship with an older woman, however from your description, it seems to me that she's more interested in having a good time than participating in a serious relationship.
If you're interested in something more than the "friends with benefits" you mentioned, I would suggest that you talk to her and try to find out what her actual intentions are for the relationship. It may turn out negatively, although at least you would save yourself a potention let-down in the future.