"Stats don't affect defence" and "Void 1 is as good as Void 5" is factually incorrect - by being in a Void Stance, you switch your potential Fitness test to Void Fitness, which means that you use Void as a basis for a Crit-reducing roll, which is your defense against real wounds.
As for Center/Predict being their own actions...I like how these actions work, but I have mixed feeling about aciton economy in duels. But I will test it out first before talking too much.