Looking, but no luck. There is one thing, all the pics i posted i got from a Luftwaffe site that only posted German AC. Maybe you got it wrong.
I don't know what it is, but the lines of the aircraft are really characteristically Italian. From no other country do you find that distinctive roundness to the fuselage, and especially the canopy and rudder shape.
Looks like a pair of Macchis or FIATs thrown together.
The tail gun is indeed from a Heinkel and it's a 7.92mm MG17. An MG151/20 20mm was almost 6' long.
Also the last one is a Bf 110. There was some more extravagant nose art to be found on German aircraft during the Battle of Britain. I have a profile with similar nose art (may be just from the same unit or..) listed as Bf 110C flown by Guenther Specht of I/ZG 26 in 1940.