If the engine is running too "rich", then the high-speed needle's not set correctly. Even when it's set correctly, you will get oil coming out of the pipe. After all, the oil doesn't burn, and some will collect in the exhaust system and drip out. This will be especially noticed after you shut the engine down. It's a common thing to get oil dripping from the exhaust outlet. That's wny people have been stuffing a bit of paper towel or rag in the outlet at the end of the day....to absorb the residue that drips out.

For proper tuning, you have to get the full-throttle mixture set first, then the idle. Midrange is controlled mostly by the idle mixture setting. You want the engine's idle speed to be just slow enough that you can sit the car down, apply the brake, and the engine's RPM will not sag. It's normal for the car to "ooze" off when you release the brake at idle. The clutch shoes will still tend to wipe the clutch bell and move the car. The engine should not be turning high-enough RPM that the clutch is actually trying to engage...that's what can cause the engine to slow down when you apply the brake.