I am certain that this has been done but I cannot find it anywhere. I have a motion project where I look down on some land from the sky and I want to draw a few text phases in the clouds without actually writing the text with a mouse (so entering the text in a box, hey my handwriting is really bad!) Preferably have the phrases swirl in and out or appear and vanish using particles. How is this done?
You're asking quite a lot there John, and there are various different ways you could tackle the problem.
For writing the text in cloud form, you might want to investigate using a replicator. You set the replicator shape to Image and then drag your text layer into the Source well. There's a nice little tutorial that uses this technique to make the typed word PAIN look like it's been written in blobs of blood - should be pretty straightforward to adapt it to making the words look cloudy: