Adding Click Track by Tapping - Tempo varies

I’m trying to add a click track to an existing instrumental background track that our choir is singing to. The tempo varies, so it can’t just be added at a particular BPM. I can probably just find a drum kit on a MIDI keyboard and tap along with the song. I’d rather just do something right within the computer and tap on a key there, if possible. The plan is to have the click on a hard left and the instrumental track on a hard right in the stereo field.

Another challenge that I’m running into is that this accompaniment track has rehearsal cues within the songs. The way the show up when uploaded to iTunes is each cue is a different song. On the CD it just plays seamlessly through it. I have not been able to figure out how to play the “songs” in sequence on Audacity. Also, if I just work on them in sections and get the click track added, how will I upload them back into iTunes where it will play straight through the rehearsal cues?

If you are using a laptop computer, it will probably have a built-in mic. In which case you can set Audacity to record from the built-in mic and tap some part of the laptop.

See here: Audacity Manual

See here: Audacity Manual
and here: Intro to playlists in iTunes on PC - Apple Support

Generally it is better to start a new topic for each question. If there are multiple things being discussed in a single forum topic it can quickly become very confusing.

find a drum kit on a MIDI keyboard and tap along with the song.

While that may give you a warm feeling, Audacity doesn’t understand MIDI. Either there needs to be a MIDI to Audio conversion in the middle somewhere, or you need to take steps to record the keyboard audio out.

My keyboard only has a headphone connection, so that’s what I use. My computer has stereo audio connections for recording. Most don’t. Your computer may have one really talented connection that can switch between multiple jobs, consult your instructions, but if that fails, you can get a cheap stereo analog to USB adapter such as the UCA-202.