Yeah, it's generally easier for me to reverse a gyro too, probably because you can get away with "sliding" the joystick from facing away --> down--->down and towards the opponent. I made some videos on my Wii so it'd be easiest to send them to you that way. What's your FC/Wii #?
About the backair zig-zag thing... I'm pretty sure I know what you mean. I don't think it has a specific name so I just call it dive-bombing, since that's what it looks like when you keep doing one of them just above the ground =). As soon as you bair, pressing down will make you fast fall with a noticeable difference in vertical height, something you already know. I don't know of the exact video either, but I can tell you that Overswarm was in the air, used a bair, fastfalling its animation, IMMEDIATELY used a reverse-up b (say he was falling facing right, ff-ing a bair (cstick the bair so you can ff with the joystick), then pressing up and to the left to use the up-b again), and IMMEDIATELY after that buffering or doing another bair, fastfalling it again but taking him in the opposite direction. You can chain them together if you keep doing it. Fast fall a back air, up-b in the opposite direction, and repeat.
EDIT: @Shock: I don't agree that you can press the direction, stay in the air for awhile, and then press B and still turn around. You make it sound like you can full hop, tap the other way while rising, and press b when you're about to land and still turn around when you fire it. It has a definite time frame to it which looks a little bit longer than the 1/4 second. As for method number two, it has to be much less than 1/4 seconds, which is why you can't take too long for the "hadouken" and still get the bounce. It would be interesting to know the frame stuff for this.
Have you seen the Japanese Snake videos where they do this but with pulling out grenades? I've never been able to pull it off with ROB's neutral B and get the turn and the bounce together