My aerial game is weak. Very weak. I really dont know anything about, so I generally avoid courses that call for it.
You can use the side attack (double tapping R or Z as you put it) on the ground though. You can use side attacks continously to make turns that are too sharp to drift through without losing much speed.
I think a really good course to practice all the speed techniques is Silence 2. At the very beginning, you can railslide a bit to gain some speed. Then comes the fun drifting part (huge spiraling turn). When you get out of the drift you should have quite some speed (At least 1200, but I'm sure you can get much more out of the drift if done correctly), but up ahead are some really really sharp turns. So what do you do? Side attack through them! The last test, space flying, is at the wavy bumpy road near the finish line. You can get some air off the top of a bump, *insert crazy insane spaceflying skills of the master here*, and land in front of the finish line, with a ton of speed, ready to drift that huge spiral turn again on lap 2. Otherwise, just drift that final turn, but feel bad while you do it, for you have not mastered the awesomeness of space flying!!! (I wish I could space fly...)
I still don't really have this course down, as my time is still a whopping 13 seconds off of the world record, but it has certainly helped me to get railslide, drifting, and side attacking turns down.
I think you can safely assume you're getting the hang of it when you get around 1:20, and that you've mastered it like PiccoloCube if you get around 1:10
hope that helps
oh yeah, and if you have ANY tips for aerial, please let me know, because I just don't get it at all...