Help with a modern war / ammo map?

In particular, I'm trying to create a support unit akin to the Sergeant from Return to Castle Wolfenstein. Whichever form of ammo I use, I need some way for the support unit to generate Ammo Clips, as an ability (to appear either in a Backpack item slot or at his feet); it'd be nice but not necessary if there's a one-button ability to drop a clip from his inventory to his feet for another soldier's use, instead of the normal item drop method.

By the way, what's a good sort of Call in Artillery effect? (The ability = delay before it either starts getting bombarded, or simply paints a target on the minimap that the player can attack - I don't know which to use, nor what abilities & effects.)

P.S. How does one build item charges that are like those of the Mortar Team's Flare?