Question: Can I edit a Tween shot, or is the result just a 2D image?

Tweens are genuine shots; that is, every Tween frame you see in the Shot Manager represents an actual setup on an actual set, just as if you had manually tweaked the position and poses of objects on the set and repositioned the camera for each Tween shot. This means that if you click the "Edit Shot on Set" button for a Tween in Storyboard Shot Manager, the program will reload that set so you can make any changes you desire.