I'm pretty certain the halftrack uses different hardpoints for it's barrage modes(regular, incendiary and smoke).
It does. There's 4 hardpoints, one for auto fire, one for barrage, one for incen and one for smoke, hence the 4 different vet levels.
a hard point doesn't all have to fire at once.
like a sherman with .50 cal has 3 hardpoints, coaxial, gun and .50 cal and they can all fire at the same time but the mortar ht has 4 hardpoints and they are all available at the same time but because it's an ability, it has to be clicked to activate.
like a howitzer actually has 2 hardpoints but hardpoint 1 doesn't fire on its own.