I'm actually fairly impressed. I've broken/scratched CD's on purpose before, and it's actually not very easy to do. Especially with nothing but teeth!
I do.
IF I remember right, the Homebrew guys are pretty anti-piracy (officially). I'm pretty sure you need the Homebrew channel, and then another application loader on top of that.
Slim, but non-zero. If you do your reading, it's not something I'd worry about overmuch, especially since a Wii can be replaced pretty easily.
In my opinion, playing backups (or "backups" ) using Homebrew is not worth it. It took me an hour or two to get it working, and even then I was not satisfied with the performance. I'd get frequent freezes and such when using the loaders, and when I could get the backups working, I'd have weird gameplay issues. I have no idea if the problems were my fault or if they were inherent to the software. Perhaps things have improved in the past year or so since I messed with it. Anyway, you're obviously welcome to mess with it if you want, and it's probably not very risky, but I didn't have a very good experience.
As an alternative, you might try the Dolphin emulator for your PC. If you have a fairly modern computer, you should be able to play Wind Waker at full speed with very few visual glitches. Dolphin has come a long way.