Per scene in Unity3D, I always require some base class implementing interfaces and functionality such as delegating events for changing scenes via Application.LoadLevel().
Typically I’ve attached these scripts to the Camera; however, I’m not sure this is a best practice especially when multiple cameras are present.
How is a base class for a scene specified?
When the scene is selected from the project no components may be added nor any option available in the inspector.
How would I subtype or attach a base class directly to the scene?
Likewise for an entire Unity3D project, is there any way to base class or subtype to enable code for a Unity application independent of scenes?
Scripts must always be attached to Game Objects. Seeing as Game Objects can be parented you can group your cameras under one single parent and apply your scripts to that parent.