[@jynmi88]
Chosen are naturally more resilient and stronger than average humans, and that's before factoring in their elemental attributes. As far as a power level goes, I'd say that they'd be much more akin to benders from the Avatar series.

When it comes to meshing the elements, I'd say anything that's not completely contradictory (IE: light and shadow) could combine in at least some way shape or form. (IE: water+fire=steam)