(first things first: I'm a professional, so I'm already quite familiar with after effects. I take this class to learn more about your way of work and your theory. And I definitely learned really helpful things that will help me in future. So thank you!)
1. My Animation
I tried to tell a little story rather than to create a meaningless loop but also to keep it as simple as possible.
The plot itself is quite cheesy: A lot of strangers (Dots) move past each other, but two of them collide accidentally and recognize that they just found their love. (I wore a pink shirt when I came up with it, so that may be the reason for those feels :D)
The collision and morph to the heart basically use the principles and properties you talked about. Hope you like it. :)