Grain Mill
The grain mill will take one wheat and turn it into four Grains (ore:itemGrain).

Furnance
itemGrain = Roasted Grain (roastedGrain)
roastedGrain = Darked Roasted Grain (darkenedRoasted)

Brew Kettle
roastedGrain + water = Ale Wort (basic)
darkGrains + water = Ale Wort (stout)

Have the ratio between wheat/other into Grains adjustable
Allow adding other items to the list - grains from other mods

Will do. It will also be ore dictionary.