From: Evan Koblentz 
  1. How rare/valuable is the item? 
Moderately rare, not very valuable.
  2. What else might be inside the package? 
Nothing - it's clear shrink-wrap around a loose-leaf manual.
  3. Will opening it cause any damage? 
No.
  4. Can you store it in a suitable way after opening?
If I open it, I plan to store it in an original DEC three-ring binder.. :-)
  From: Fred Cisin 
  OTOH, if you want to SELL it 
When it comes to me and PDP-11 stuff, 'cold dead hands'! :-)
        Noel