<<Can any of you point me to instructions/ tutorials
  that might guide my efforts in removing fish-eyes or
  otherwise restoring clarity to Plexiglas?>>
  
Some years ago 3M introduced a plexiglas polishing system at OSH.  The demo
was impressive.  They would put a deep scratch into a piece of plexiglas,
and then with an electric orbital sander, soapy water, and progressively
finer grit specialty abrasive disks, they would take the scratch out and
then polish with a finishing compound ("Finesse-it") and polisher.  Took
about 5 minutes in the demonstration.  I was impressed, and bought a kit
which remains in the drawer.  

I went to the 3M web site and was overwhelmed by choices.  Perhaps others in
the LML community can point you to a specific part number.  

Fred Moreno