Pot metal - they switched to plastic in 1972. This per Joel Cooper when he restored his 1971 and 1972 340 Canadian Darts.
Yep, cast or potmetal. Although chrome plated early on, they did drop the chrome from a lot of the indoors potmetal bits. Inside rearveiw for example.Chrome are metal for sure.
That one I can solve. At least for my 1970 Darts a lot of the wiring for accessories is included in the various main harnesses. This means that for many Mopars there is just one dash harness or one under hood harness or rear harness and a bunch of the wires/connectors go unused. This is true for wires leading to the AC sub-harness, to fender top turn signal lights, rear air, map and other "extra" lights, trunk light, etc, etc. for my Darts. It isn't always that way - I help a friend install new front harnesses in his 70 Superbee and he had a choice of harnesses with or without fender top turn signal lights - go figure.! My car is wired for rear defrost but the blower and switch is missing.