Why do you need 5 points?
A curve like that would be smooth with just 3 points. And it would still have a wide range of motion.
Depends on if you need sharp bends at the joints. Using the curve tool you can animate the "curviness" of the spline at a point if needed.
If in smoothness you mean that sort of "lumpyness" from changing the width of a stroke... er... no. Not much can be done about that. It is sort of the nature of the beast.
If you peak the ends of a spline the curves and varied width strokes look a little better.
Forgive this silly and totally pointless animation. Was trying to interprete your sample image.
http://www.lowrestv.com/moho_stuff/curvy.mov
-vern