Right, the forward cowl vents started on the P-39L model. I have since seen the black dot/hole on other P-400s in New Guinea. Still don't know what they are. Probably a vent.
Here are some more RAF Airacobra 1 shots. Note the "line" between the two camo colors; these are brand new aircraft with no weathering or fading seen.
And yes, we did send P-39's to the Med. I have read a very small amount about their operations there. Also, we had some P-400's left in England when Operation Torch came up and they were suitably configured with external tanks later markings and sent there.