The silver thing is the Vanos solenoid/control unit (it's electrical) the actual Vanos is a piston & a spool valve that adjusts the intake camshaft timing. If it's just a "hum" that's normal - if it clatters after reving it - you might be using to thin an oil.
What you saw on a humid morning is the condesation/moisture that accumulated overnight. (as hot exhaust cools down, cool air gets sucked into exhaust forming condensation) If you see a little puff under hard acceleration that's normal.
NOTE: FUEL = Black smoke, Oil is blue, coolant is white or steam