Have fun, John!!! Quintet playing is something I've always enjoyed, but don't get anymore due to a lack of those big huge things that look like they could heat your house.
Intamacy is the big issue. Being able to converse musically with your first player. Recognizing when you are a soloist and supporter, and being able to adjust your playing within that context are key. (No pun intended...). If the first uses a Bb, you should, too.
Remember always that YOU have ownership in the ensemble as much as anyone else in the group, so don't be shy to speak up in rehearsal if you need to work out something or feel something is not right.
I'm happy for you!
