Cid is the only one that doesn't make any real logical sense on how he survives but then again we do see him again a few times after that. As for Yang... don't forget that if you go to the Sylph cave before the Tower of Bab-il you see Yang alive but gravely injured (which opens up the "Spoon Dagger" quest) and you see his fate. This, to me at least, would fall into the "You're not dead but you can't help anymore scenario".