The PZL P-11c like other fighter planes of the Pulawski family wasn't going to be armed with four MGS. The basic armament were the two MGS intalled in the fuselage. The exception was P-24 that could be armed with a couple of different weapon sets. However the two MGs were still the basic one. In attempt to get a better firepower of P-11 fighter the two additional MGs in wings were added. But it really affected the flight characteristics but not that much it is believed in my opinion. But you are right, these were dismounted often. Regarding the pic above, yes it was taken in 1938 before the September Campaigne started in 1939. Because there aren't too many pictures of the 4th Regiment, 142nd Fighter Squadron planes taken in 1939 during the German invasion there is no proof the wing MGs either were there or not. IMHO these were still there.
Regarding the radio set ... the squadron and section commanders had the equipment installed. Skalski was the section commander and his P-11c had the radio set mounted.