HI BlueAngel, and welcome.
It will be interesting to find out what you choose to do with your invitation to join a poly relationship. Even though you don't have specific experience with this type of structure it seems you are at least open minded and that's a terrific place from which to start.
Lots and lots of people are bi curious or find themselves somewhere on the continuum that they were not expecting. You will find your way and will determine what level of openness with friends, family and lovers feels right in your heart. Many of us start out more discreet and move toward complete openness, it's a process and a journey. FOr me I think the last unconquered frontier is the FB status and that is blank simply because there is not way to accurately describe my loves
Good luck, update us when there is news, we can all learn from you!