While I cannot hope to match the sophistication of all your answers here, which I have enjoyed reading, I can add a bit of information about the A6M and measures designed into it for streamlining. For a 1939/1940 design it was very much state of the art. It was fully flush rivetted and where necessary measures were taken to cover any protrusions in the aircraft's surface. An example of this is the pilot's entry into the cockpit. This was achieved by retractable spring loaded pegs that sat flush with the fuselage side until a button was pressed that ejected them to enable the pilot to climb into the cockpit.
Detail fuselage centre section
Even the latch for unlocking the canopy had a streamlined acorn fairing fitted to it.
NX712Z 21
In lieu of leading edge anti stall devices, the Zero did have washout incorporated into the wing. Also noteworthy is the attachment of the underfuselage drop tank, which Mitasol has already covered, so no need to go into that.