NO! Equipping an item to an Outfit slot will still leave the item in your inventory, but you can save it at your house vault and log in all your alts and wear the outfits, you don't have to buy outfits for all your alts!!!. This will allow you to trade those items to other players, store them in your bank, etc., although items that bind will need to be bound to you before you can equip them into Outfit slots. You only need the items in your inventory at the time you equip them.
