How to resupply

[Walrus]

You should read the instruction manual that comes with the game. All the details are in there.

Just quickly though:

You can resupply as soon as there is some ammo expended, it doesn't need to be all gone.
It resupplies the first of your weapon slots first, and then when that is full, it does the next slot, then the next.

If more than one unit is close enough to the ammo unit to be resupplied, the ammo dump will always supply in this order - B0, then B1, then B2 , Then B3 etc.

I think you can be resupplied from 2 hexes away, but that is slower than one hex away, which is slower than being parked (stacked) on top of the unit.

As Chris said - these units can be killed and when they are fired upon, the explode causing potential casualties to any unit within 2 hexes. The bigger the ammo unit (box, then truck, then dump) the bigger the explosion.
Enemy air units will always target these units if they see them (if playing the AI).

Ammo boxes can only supply smaller types of weapon. Up to medium size mortars IIRC.
So they are good for troops but not for anything bigger than med mortars. If you want to resupply larger arty units, helos etc, you'll need trucks at least.

The bigger the ammo type, the slower the reload.
The further away the unit, the slower the reload.

Hope that helps.
Read the instruction manual...it has heaps of good information!