Spitting oil through tailpipes.

Well, if you only have breathers on the engine now, the crankcase pressure is going to push oil vapors out and they'll go under the car and out the back. Probably explains the oil on the bumpers. Disconnecting the evacs probably caused that to show up. Yes, the whole back area is a low pressure area.... drive down a dry dirt road and see where the dust collects.

As for the tailpipe, those tips do that all the time! They are forming a low spot where any small amounts of exhaust oil will tend to collect/condense, then drain out along with water vapor and soot from the normal combustion process that naturally collects/condenses there too. If this is your drip out of the tailpipe, then that seems easily explained.

The smoke at the shifts might be from the intake... seals or intake leak: a classic symptom... or is just an over-rich mixture that is 100% normal when any carb is suddenly closed. If it's oil, such small amounts would immediately burn off in the cylinders. No smoke under load should indicate that the rings are sealing well.