FIRST THING ... I’ll bet most of you posting here have done more brake work IN A COUPLE OF MONTHS than I’ve done in my lifetime!
But let me ...
What happens to all that old junk fluid AND TRASH in the bottom part of the caliper during the flush process ?
Shouldn’t the caliper be removed from the brackets and turned 180 degrees to get everything out ?
Depends. Does your OCD let you sleep at night if you don't? Unless the system was really nasty, I just run it until I get clean fluid. I suppose one could pull the caliper and shake it up or turn it upside down and pump some fluid through. If it's that bad, maybe need to fix or replace the components.
If the results don't match the theory, change the theory.
... 
