I've run around 8 encounters with a shaman and his spirit, and many questions about it's properties have been raised.
Is the spirit unsubstantial? Does the spirit float? The spirit is supposedly anything the character wants it to be so if they pick an eagle can it fly and attack things hanging onto the ceiling etc.
Does anyone know of any relevant rules? Have any of you encountered these issues? What were your rulings?
The spirit is not insubstantial (in the strict sense). I.e., damage done to it isn't halved. Also, enemies can't move through its square, so it's substantial. It does, however, float: since it's a conjuration, and conjurations can float, the spirit companion can as well. Even if it's not a critter with wings.