[Avodah] primitive concepts and missing letters

[David Riceman]

Two questions:
  1.  In logic a primitive concept is one which is used to explain other 
concepts, but which is not explained by them.  Is anyone familiar with a 
list of primitive concepts in aggada?

  2.  Over Shabbos I was reading something by the Rokeah (the rishon, 
not the aharon) where he is doreish psukim based on which letter fails 
to appear in them.  I am aware that the Zohar does this, but as far as I 
know the Rokeah never saw  the Zohar.  Is there any precedent in Hazal 
for this?

Thanks,

David Riceman