Since Dan answered his own questions I'll answer VM's
1) Attached xrefs are visible in subsequent xref'd drawings while ovelays are not .. i.e.
Attach A to B Attach or Overlay B to C you will see A
Overlay A on B Attach or Overlay B to C you WILL NOT see A
2) The space that represents the view of a drawing that would be displayed on a paper plot, as opposed to the space where the drawing of the model resides, hence PAPER space and MODEL space
Now .....
Ok..I'll have to word this in a way that you will understand, but not give away the answer ...
3. Assume you have a 3x3 grid (actual dimensions are irrelevant) in model space with 9 equal areas. How would you handle placing an attributed block in all of the grids, yet only have one attribute?
4. How would you globally change the style of every dimension in the drawing from one predefined dimstyle to another predefined dimstyle?