Re: Keep your hands in front of your center?
There is a concept called "centerline" and "center-line triangle."
Having your hands in front of your center means having your hands along centerline and structured in a way that they move with your center and not independant of it. Centerline triangle is formed when you outstretch your arms in front of you and touch your fingertips together to form a triangle with both arms as sides and the linde between your shoulders as the base. Most of the efficient power generated by the body is manifested within this space formed by the triangle. And to avoid incoming strikes all you have to do is move the tip of this triangle out of the way and the rest of your body is also safe. Think of a wedge.
There are other uses of these concepts in every technique you can imagine.