Gray Concrete Powder is a shapeless crafting recipe that uses 9 items: 1 Gray Dye, 4 Sand and 4 Gravel. The position of the ingredients does not matter — put them into any free slots of the grid. It needs the full 3×3 grid, so you have to use a crafting table.
You need 1 Gray Dye, 4 Sand and 4 Gravel — 9 items in total, arranged as shown in the crafting grid. The recipe gives you 8× Gray Concrete Powder.
Yes. The recipe needs the full 3×3 grid, which only a crafting table offers.
It is shapeless: the ingredients can go into any slots of the crafting grid.