Hello Eric . . .
Starting the history of koi pond filtration and pre-filtration with the seven elements you've selected would be like writing the history of the human race and starting with the 1900's.
The history of koi pond filtration starts with NO filtration at all -- and traces all manner of technological upgrades, innovations and deadends right up to the present day.
To see what I'm talking about, check out this thread:
Filtration: From the Beginning JR 11 Aug 2007 http://koishack.com/forums/index.php?showtopic=11956
I think you'll find the answers to many of your questions there -- and the context within which to understand and appreciate them.
Best wishes,