My advice to you is to not fixate on the label. It shouldn't define you, so don't spend time thinking too much into it. Focus on how you're going to deal with your new feelings for your best friend.
Yes.
Pansexuality and Zoosexuality are two that I can think of off the top of my head. Zoosexuality is kind of a sensitive issue though, considering what it's all about. It technically is a sexuality though.