Hi, guys,
I never heard the man pronounce his own name, but the colonel who introduced me to him at an AOA convention pronounced it GAR-und, with the first syllable as in "Gary". Mr. Garand did not object, so I assume the colonel was correct.
Most WWII and later GI's called the rifle just the "M1", and that term was always used for and understood as referring to the rifle. I served too late for WWII, but I never heard any soldier call the rifle anything else. If a soldier said, "I have a problem with my M1", you knew he was not referring to anything but the M1 Rifle. Early on, people like Hatcher called it the "Garand" to distinguish it from the Springfield or the Johnson. Today, only newbies call it a Garand.
The M1 Carbine was always "the carbine" (pronounced "CAR-bean") unless an armorer wanted to distinguish specifically between an M1 carbine and an M2 carbine.
Jim