re: “Was the audio channel(s) from the moon ship to earth, FM and Frequency Modulation ? Certainly weren’t AM transmissions.”
FM, and transmitted using part the “Unified S-band System” radio system. On the Unified S-band radio system telemetry and voice rode on various multiplexed “sub-carriers” ... previous to Apollo the voice comms and telemetry were on different radio sets and frequencies.
https://www.hq.nasa.gov/alsj/alsj-NASA-SP-87.html
A better, plain English description of the Unified S-Band radio (and data) system:
https://www.ab9il.net/aviation/apollo-s-band.html
BTW, it used PM (Phase modulation) which can be called a modified form of FM, both of which use a “constant envelope” signal as contrasted with AM whose envelope varies according to the modulation.