is this technique I describe actually superclass acessing subclass data

No.

Superclass objects cannot get to the constant - only objects in the sub-class in question.

What you are defining is an abstract interface - every Question class should have a get_table_name method (or whatever your constant is called).

Each sub-class is then giving its own concrete implementation to get_table_name (or whatever).

It's a commonly accepted technique.

Take a look at Refactoring: Soft-code class name in factory method and Re: Re: Extending object you don't create which do similar things with class names rather than table names.