@nprofile1q... Hey, this runs on my laptop that's from 2010. Most online demos either give me a black screen or run like powerpoint presentations, so congrats.
+1 for the mutate-and-fade, I'd imagine that will be a big help in managing draw order.
Also, for the fade-in/out, have you experimented with making the t of the transition proportional to the distance of each cloud to the camera? Looks to me like you have a trigger for the switch and then the transition happens in a fixed amount of time?