Brain,
Looks like others have answered question "1" - a "sandwich" governor per Jon (carbking).
As your picture seems to clearly indicate a GMC 6 cylinder, a little web searching I did may have your answer to question "2" - I believe that fitting you pointed at is were a PCV pipe was connected that was further connected to the valve cover (see the 2 pics attached below on why I came up with this thought).
One of our fellow GMC guru's will hopefully come along and provide confirmation and maybe a bit more detail (or correct me if I'm in error).
