In theory an infinite amount of different waveforms. But practically speaking, no one would be able to distinguish them by ear, and even oscilloscopes have limited resolution.

Music is super complex and can't even be described by a single or a few waveforms, unless it's very simple. Another simplified way to explain all the sounds of music fitting on one "waveform" is to imagine the high frequency stuff happening in between the low frequency stuff. And usually the different instruments and voices don't happen all at once, they happen slightly one after another, or in sync but intentionally so they affect each other the "right" way. Whatever the "right" way is...

Definitely, but you only ever perceive all that because of the one-dimenaional way your eardrums vibrate, and they vibrate because the air next to them vibrates. If we make the air next to your eardrums vibrate in the same pattern they did when the band were performing, you will hear and perceive the same sound as the band made.

You should be aware that an amplified band is only ever making sound at you through a bunch of speakers whose only function is to vibrate air in a one dimensional pattern.

Separating that all out into different instruments and people and timbres etc is the clever bit, and your brain does that, not the speaker, and you largely learned it as a child.