[Shane Scrimager]

I had a project with the same idea. Money flying out of a suitcase as the animation ran through the frame. Your project sounds a little more time intensive but this will work.

Create a Particular layer with the custom shape of EACH different post-it note.
(I think if you had 10+ there would be enough difference to make them look individually written. If you had 20+ Particular layers each with different writing it would definitely look better.)

Have each layer react slightly different with gravity, wind, emission, z-space and so on.

Hope that helps, it worked great for me!

Shane