As to Metric vs Imperial
With a background in the metal fabrication since my parents inception, I understand both and prefer Imperial over metric for many reasons, one being I am a just an odd ball to start with.
However, when it comes to measuring devices the non continuation of numbers is simpler to train people in the field to use because they make lesser mistakes flipping numbers around, because of the layout.
This is based on over 40 years of Clients sending me their field measurements in all day long, and I see many less mistakes from those using imperial than metric.
So metric might be simpler to read and use, but simpler sometimes does not train the mind to think, at least it seems from what hits my desk daily.