Audio channels is the correct term. You might hear audio producers talk about multi-track audio (which means more than two tracks) or stems.
It all goes back to tape editing, when independent audio signals needed their own track. Stereo is a special case, where one track is designated for the Left speaker/output and the other track is designated for the Right speaker/output. Surround is a special case as well - specific channels are dedicated to output speaker positions.
A piece of music may be composed with dozens of individual tracks. Most DAWs support the concept of stereo tracks as well as mono tracks, so don't get hung up expecting that the number of tracks in a stereo project is an exact multiple of two.
When you take a multi-track project and create the final output (whether Stereo or Surround), the arrangement of the mixer is called the mix down (because you are mixing many tracks into few). The process of actually recording the mixdown depends on the DAW. Some call it rendering, some call it bouncing, some call it exporting.
Yes - they are audio channels. Are you separating sound effects from background music etc. or placing each of these into channels for each speaker (eg 7.1 surround sound will likely have some background music in each channel, whereas a sound effect may be only in the front right and so on)
Audio channels or audio tracks. It depends on who you're talking to.
Please let an audio post engineer mix it for you!!!
