"An exhaust brake is a means of slowing a diesel engine by closing off the exhaust path from the engine, causing the exhaust gases to be compressed in the exhaust manifold, and in the cylinder."
This can be done with a variable turbo or an external butterfly. It doesn't matter how the exhaust is closed off just as long as it is closed off.
All of the exhaust brakes on Ram/Ford/GM are part of the turbo. There isn't a OEM exhaust brake that isn't.
The Dodge 5.9L started with a DIO (dealer installed option) exhaust brake that was first controlled by a mechanical switch and later the ECM and attached after the turbo. Originally they were on manual transmissions only and became DIO's for auto's in 2006 and OEM with 2007.5 with the 6.7L.
Yes they should be used often to allow the vanes to fully travel to reduce soot buildup. I'm not sure about Ford/GM but Ram does have programming that moves the vanes at startup; however, the best thing is to use them.