Quadratic Functions (Graph & Equation Anatomy)

Applet contains 3 sliders: "a" slider, "h" slider, and "k" slider. The equation of any quadratic function (with "a" not = to zero) is ALWAYS a parabola. Move the sliders around to see the changes in the equation of a the displayed parabola. (The equation will change as you move any slider.) Questions are contained below the applet.
Questions: 1) How does the parameter "h" seen in the equation of the parabola? 2) How does the parameter "k" seen in the equation of the parabola? 3) What effect(s) does the parameter "a" have on the graph (parabola)? Explain in detail. 4) Are the coordinates (x, y) of the vertex of the parabola made evident in its equation? If so, how? Explain in detail.