re: system pressure check :  What pressure should be used
and how should this
test be done non-destructively?

This is described on page 19.17 in Bentley manual and it
says 1 bar (14.5 psi).  Apply pressure to expansion tank.
Since the cap on the expansion tank will "open" at a greater
pressure anyway, there is no need for more. It makes sense
that a system pressure check be done at the point of the
"relief valve," which is the radiator cap or sometimes in
newer vehicles the expansion tank cap.  If your engine
creates more pressure than the cap will hold when it's
running, it's boiling over.  This information (except for
pressure figure) is generic for probably any water cooled
engine in any car or truck.