Can the Ammo items only be used when you're using the Z3 Subscreen? Or can you only collect them while you have Bombs/Arrows? I'm guessing they can only be used on the Z3 Subscreen since Bombs could be bought as Ammo, and Arrows can be found before you have the Bow in A Link to the Past...
Also, how do you access a map while you're using the Z3 Subscreen?