It is quite useful for all levels of gear as reforges provide greater stat boosts the higher Rarity the. However, an item can have only one reforge.
Any selected powers that are not usable in the current spec are. At A Glance Power List: A window listing the complete descriptions of selected traits has been added to the Azerite Power UI Window. Now, I did nowhere near that much reforging last week, and it was on the order of 80g the last I checked.
