For the 4 islands in Manila Bay that used to be the Manila Bay Defense Forts, Corregidor-Ft. Mills, Caballo-Ft. Hughes, Fraile-Ft. Drum, Carabao-Ft.Frank.
Zf930. The man in the center is indeed the correct age to have been a WWII veteran in 1966. A web search tells me that the Iowa Governor in 1966 was Harold E. Hughes and he was in office from 1963 to 1969. During WWII he served in the US Army fighting in North Africa.
Zf939. This photo looks exactly like what you will see if you walk along either the north or south ventilation shafts of the Central System or parts of the QMC laterals. There appears to be an intersecting lateral on the left-hand side. (courtesy LIFE magazine)
Zf936. This is no work activity to be seen in this undated photo. Mid 1930s might be a good guess as the West entrance is complete and civilians are still on the island.