Is the Orange Guidance Soapstone item consumable?
It is not a consumable item, although you use it like one. That is to say you need to have it equipped in one of your item slots, and use it with the item-use button. So you could think of it was a consumable item with unlimited uses.
You don't have to equip it, like every other item. Equipping is just for quick use, but you can access it through the item screen.
And you only need one throughout the entire game.