I can only answer #3 since I'm not old enough to have experienced #1 or #2.
The M-16A2 is almost impossible to control on full auto. Even on burst, the third round can be a flyaway. Moreover, the weapon was NOT designed as a machinegun and thus has no real need for f/a fire. You are correct - the SAW, M-60 (phased out in the Corps), and 240G are used to lay down a heavy volume of fire. Plus the MK19, mortars, and M203 can be used for indirect fire. Remember, artillery/indirect fire causes the greatest number of casaulties to infantry.
I personally, rarely will put the weapon on burst, preferring to take slow well aimed shots when possible. Even in close quarters, the burst function isn't utilized. There are thoughts of replacing the SAW with a heavy barrelled M-16 but so far nothing's materialized yet (still testing I believe). Finally, if the M-16A2 was frequently fired on F/a I believe the barrels would wear out rather quickly. I hear the SEALs have this problem with M-4's that have this capability.
The M-16A2 is almost impossible to control on full auto. Even on burst, the third round can be a flyaway. Moreover, the weapon was NOT designed as a machinegun and thus has no real need for f/a fire. You are correct - the SAW, M-60 (phased out in the Corps), and 240G are used to lay down a heavy volume of fire. Plus the MK19, mortars, and M203 can be used for indirect fire. Remember, artillery/indirect fire causes the greatest number of casaulties to infantry.
I personally, rarely will put the weapon on burst, preferring to take slow well aimed shots when possible. Even in close quarters, the burst function isn't utilized. There are thoughts of replacing the SAW with a heavy barrelled M-16 but so far nothing's materialized yet (still testing I believe). Finally, if the M-16A2 was frequently fired on F/a I believe the barrels would wear out rather quickly. I hear the SEALs have this problem with M-4's that have this capability.