For the first effect, Google "Plexus Art of Flight tutorial" - essentially you link a Light to a Noise Effector and use the Light to distort text. For the second idea you have, this sounds quite simple. Is there something specific you're not familiar with, with Plexus or AE?
I am familiar with after effects (somewhat) by now, it's just plexus I'm clueless about. There's a few spotty tutorials on how to work with text and plexus but not plexus itself which I would really love to learn. :)
http://aescripts.com/plexus/ There are quite a few tutorials on how Plexus works here. The best way to a learn the tool is to learn how it works and then take that knowledge to apply to your specific task. Just learning how to do the 2 things you want is great, but you'll be back next time you want to do something. Rather, spend the time to learn Plexus and how each feature works, then no matter what you're hoping to accomplish, you'll have a great foundation and the rest will just be thinking through how to make it work.