The idle before shutdown applies to any turbo... that or install an oil accumulator. It will keep pushing some oil to the turbo after shut down.
The water seperator is a really good idea...
I'd leave the boost on the turbo alone. Especially if you don't know what kind of condition the engine is in internally.
You can try Helms for a service book. They print for more than GM. If the turbo is aftermarket you'll need to contact the maker of it.
try www.api.org for more info about current Diesel oil service codes.
11-Sept-01, The day the world as we knew it ended.