I am not sure about how you are painting your weights, but if you want to post a link to your file I would be more than happy to help you with that.  One of the most important things to do when setting up a NCloth animation is to set your Nucleus Scale to fit your scene.  If you are using Mayas’ default setting CM than you will need to set your Nucleus scale to .01
NCloth Nucleus is scaled in Meters, so 100 cm = 1 meter.  I hope this helps with your results.

Falling is due to gravity set up by the nucleus.  You can set the air resistance of the nCloth (Leaf) to adjust how fast it will fall and how it will be affected by the air resistance of the global variable also found in the Nucleus.  Think of the nucleus as setting up your environment (WIND, AIR RESISTANCE, GRAVITY).  You can wind (X,Y,Z) along with some randomness that will give the leaf a much more realistic animated look as it falls.  This is Trial and error but, a good animation for a beginner.