Edit#2: Also, you mentioned using the AddItem variable. The player isn't going to get any items from the NPC. So will using just RemoveItem automatically make him take and equip these items?
No, you have to use both functions.
To add an item to your NPC's inventory: NPC_ID->AddItem, "item_ID", 1
To remove an item from the player's inventory: Player->RemoveItem, "item_ID", 1