I seriously doubt that they would have both versions on one disc.
I don't. It's much cheaper (production/distribution wise) that way. They can charge more for a Wii version at launch than the Gamecube version.
It's Zelda. They can charge whatever they want for it, and people would still buy it. Even if they are shipped on different media, they'd still be priced the same, otherwise people would just by the GC version.