Your post #3 fill the fuel filter. NOT on one of the common rail engines. They are made to bleed with a fuel pump through to a bleed port. The reason being that 7 micron particles destroy the injector tips. New engines do best with 4 micron filters, a lot of them come with 7 micron filters, but not good, that was a case of managers trampling on the engineers, over cost. I have a few stories about getting sloshed with the European diesel engineers, who where having no end of grief with the chassis engineers about filter requirements, i.e. how many, what micron size, and where to be installed. Older lower pressure systems no problem, they will take a lot more before they die.
When I was working I had to specify diesel engines for mining equipment, on their ability to be approved by the mines inspectors, re: emissions.