If the water doesn't have the same feat as fire, and there's no explanation or statement linking the destructive capability of both, then no, the water wouldn't have same AP as the fire. Again... You need a statement or showing proving Output of Energy is equal within the energy system. You already have scaling itself down, as they can damage characters that can tank their attacks with any attack they use. What you need is to show that the energy they use for creation is the same output they use for attacking.
This proves all her techniques come from the same source, yes. It doesn't prove she has the same output as her creation stuff. So no, we can't conclude that.
They increase their physical strength with this energy. Do they increase it at the same rate that they apply when creating stuff? That is the question here. Fortunately, you already bypass this through scaling, as they damage each other with energy attacks as much as physical ones. However, there's still the caveat of proving Creation feats scale to their energy usage. So far, only Kuuvahki shows this.