question about spotters

[Imp]

Does this refer to "spotting" for barrage / bombardment? Does this apply to FO type units?

This sort of question would be easier to test than ask but yes all FOO types including Light Helicopters can call. Also most leaders the x0 can but are not as good as FOOs, there are a few unit types that are not allowed to call it in.

Secondly, it appears that there can only be one spotter for barrage / bombardment for all artillery, mortar and arial bombardment units.

You can use as many diffrent units as you like to plot arty opening the bombard screen & ploting their adjustments. If you want to use a diffrent unit to plot some select him & repeat for what he is adjusting calling.