When trying to rotate using 2-D Rotation, I get the message "Unable to add effect: The duration of the effect track cannot be more than the duration of the video track. You may have to shift one or more effects or clear the effect track to make room for a new effect." The effect track is clear. How do I control the duration of the effect track?

It is possible that the effect is very small. You may have to zoom in to see the effect. You can also clear the entire video effect by selecting Clear Effect from the Edit menu. Make sure that the effect track you want to clear is highlighted. Now you should be able to add effects.