It's good practice to only expose what is necessary. In a commercial environment this is even more important as you must support what you expose. Based on this line of thinking I would only expose classes outside of my package that need to be accessed outside of my package.
As for
Java Doc comments. I would add Java Doc in exactly the same way to all my classes regardless of what the access level was on them. Reason being is that
you should document all your code for other developers who come to read your code at a later point.