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1. Turbo shaft play of less than 1/16 inch side-to-side sounds okay. Front-to-back (in-out) play is more worrisome. The shaft rides on oil bearings, which have an outer diameter slightly smaller than the inner diameter of the races in which they fit; the gap is filled with oil when the engine is running. With the engine off, a small amount of side-to-side play is normal. (Obviously, you can't check play with the engine running; you'll lose your fingers.) Here's a photo of the front oil bearing in a Garrett T3 turbo from an OM617 In this photo the bearing is shown halfway out of the race.
2. I don't see how you can disconnect the turbo from the intake manifold and still safely get intake air from the air filter to the manifold. With this engine/turbo design, 100% of the intake air (excluding that which passes through the EGR valve) goes through the turbo at all times.
3. Unless you have significant front-to-back play in the turbo shaft, the likely source of oil in your intake system is not the turbo, but the air filter housing. Oil particles in the blowby gas from the valve cover are supposed to be collected by the separator in the air filter housing and drained back down to the oil pan. But the separator often does not work well, allowing oil to flow into the housing, onto the air filter, and into the U-tube. And drain holes at the bottom of the air filter housing allow this oil to drip down onto the turbo and other parts of the engine. If you remove the lid of the filter housing, is there a pool of oil sitting in the bottom? Is the filter wet with oil?
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