Fantasy Superhero SoL, sounds cool and I might be interested. :) 

How would play be structured? Fully freeform, or will there be some GM-mediated structure, events, storyline, etc.?

Also, do you have a preferred choice list of elements? E.g. just the good ol' earth/fire/air/water, or also things like ice, lightning, wood, etc. (or would these just be 'flavorings' to the Big Four? e.g. lightning? sure, but that would be air, technically; ash? sure, but that would be a fire, wood -> earth, etc.)?