Is it possible to select and edit a torus that has been added to a cube?
This produces a torus that is half-in and half-out of the cube.
Is there any way to select the newly added torus to scale, rotate or delete as a whole. No entry for the torus appears in the tree view. Is it considered a part of the cube?
In edit mode select any vertex, edge or face of the torus, then use Ctrl+L to select linked. All of the vertices (edges or Faces) of the torus will be selected, and given that the cube and the torus are not linked, or don't share any common vertices, none of the geometry of the cube will be selected.
If at that point you want to turn the selected vertices as a new object you can press P and choose separate selected. A new object will be created and can be transformed independently.
What you call "tree view" is the outliner window. To understand the difference between objects created in edit mode and those created in Object mode please read: Why can't objects in Edit Mode have their own name?
If you are just starting using blender I recommend that you read trough the links on the following page: Resources for Blender
If you want a new object to be in the Outliner, add it in the Object Mode . Also, before you add it, deselect all existing objects both in Object and Edit Mode. This method is better as you don't need to worry about topology. And Outliner is so much more than selecting/deselecting.
