Unit with inventory

[chalilin]

Hi, i making a mod that add some rifleman that help the player to fight. But i want they can't shoot without ammo, then I've thought:
1. If I make them unit-type, how can I set an inventory like turret-gun?
2. If I make them car-type, how can I allow them to move like biters?
3. If I make them character-type, how can I set an ai for them?
4. Last solution, how can I make an invisible turret wich shared his position with an unit?