Answer to first question. That's hard to say for sure. How we normally check the oil/vapor seperator is with a tool called a manometer. My shop is new and that is an old tool so we do not have one. We hook up the tool to the oil fill port and run the engine.
2nd question. There is a hose that runs across for intake manifold that eventually hooks to the intake manifold. So you would have unmeter air that way. I normally don't see internal leaks but it does happen.
Do you know if the TVV fault is stuch open or close. If stuck open replace the TVV, this may be your problem.
Sorry, I don't have too much more information for you. I hope you figure it out.