No, FlAK means anti aircraft gun. He probably had to move the big spot lights or carry ammunition.
Yes, Flug-Abwehr-Kannone.
I hate fonts where I and l can almost not be distinguished.
It’s been imported into English as just a standard word, no capitalization necessary anymore. Most English speakers probably aren’t even aware it’s originally a German acronym. We just say “flak” like we say “scuba” and “laser.”