Hey,
So as for the balloon: The pop happens in about 1 or 2 frames. So you could model the full balloon, then create another model that you'd only have visible for one frame of the balloon in pieces but somewhat still in the shape of the balloon. then you might want to do a third model thats all the rubber chunks small and relaxed with the string still tied to at least one chunk, You can make this last state into nCloth if you wanted to get fancy and have it start to fall to the ground. As for the confetti, you'll probalby have best results with sprites (unless it's that really stringy confetti). so just duplicate the full balloon, delete all the faces except the bottom part. Then use that bottom part to emit particles (don't give the emitter and speed), keep pushing play until you have enough particles, then set the particles as the initial state based on current frame and delete your emitter. Make sure the start frame for the particles is the same frame as when the balloon pops. Add some gravity/ turbulence (what ever else). You'll probably want to make in image sequence of a piece of confetti spinning. Use that as the sprite and then setup an expression to control the frame cycle with something like the Postion in Y Per Particle. Anyways, hope that helps.
J