In the later 70s, I was there, and the tank was the M60, the side arm was the M1911A1 and the "crew weapons" were M3/M3A1 smg. There was also supposed to be a "dismounted" kit (tripod, etc) for the coax mg and the M85 .50 in the cupola. Never saw any of those on tanks in the field though possibly they were stowed away "deep"...
The tank replacing the M60 was the M1 Abrams, which began reaching stateside units in small numbers in 78, and didn't get to Europe until a couple years later.
Replacing the M3A1 with the M4 carbine would not have made me happy if I were a tanker. Shortened as much as possible, the M4 is still longer and more awkward in cramped places than the M3. Plus going to a 9mm pistol and 5.56mm rifle removes the small ammo commonality tanker had.
And, were I a dismounted tanker with an infantry rifle, odds are high someone would make me infantry, rather than get my butt back in a tank at the earliest opportunity. No, that wouldn't make me happy, at all.
If there is no sign of damage or deterioration, WWII .45acp ammo should be fine to shoot in modern guns, though as mentioned, its now become collectable, so shooting it for fun is kind of wasting money.
.45ACP tracers were used for training, possibly for signaling but we have flares for that kind of thing, so I don't think that was common.
One thing about tracers, they work BOTH WAYS!!! And always remember, that if the enemy is in range, so are YOU!
One of the "tricks" we got taught, (but never had to use, thankfully) was to load a tracer as the next to last round in the magazine. The idea being when you shot the tracer, you knew it was time to change magazines, while still having a round chambered while you did it. Don't know if anyone ever really did that, we never did, for one thing they never gave us the tracers to do it with!!