I sent you a PM with an offer/solution, Mumbling. B)
I Highly recommend having a copy of the song on your computer so you can refer to it easily. Since you've recorded this before with your family, you probably already have this.

If you don't, check my website for the songs (see signature).
an extremely complex and time-consuming task, unless I miss my shot by a lightyear or two
The way I did it was extremely time-consuming. If you just make a basic mockup as a General MIDI, an experienced mockup producer can make the background music in as little as 3-4 hours probably. I'm known for taking upwards of 20 hours in my background music, simply due to the complexity of the layering in my arrangements (this relates to the complexity of the virtual instruments I use, which function best when using many layers), as well as my attention to detail. I've done simple mockups of 4-minute songs in less than 2 hours before. It all comes down to how much detail you want.
[EDIT] I added some comments to my recording tutorial, which I'll post here for easy access:
"
My recording has a lot of background noise or *hiss*ing. How can I fix this?Try setting the microphone's volume lower while recording. We prefer a quieter recording with less noise over a loud recording with a lot of noise. It's easy to make a quiet recording louder. It's nearly impossible to remove hissing. Also, see tips in the next section to possibly improve the sound further.
The recording has a loud, low-pitched buzzing sound. Is your wiring from your microphone or mic cable near a source of EMI (electrical noise) such as a computer, speaker, power wiring or power source? Try moving the wire. Also, make sure the wire that connects your microphone to your computer is nice and tight on both ends. Worst case, your sound card isn't very good for recording with. Typically, laptop sound cards and some onboards desktop sound cards are pretty poor for recording quality.
My recording has a very high-pitched shrieking sound. Turn off any nearby TVs and CRT monitors while recording.
Also, if your computer is very loud when it's running (due to fan noise, etc.), try to move as far away from the computer as possible when recording."
Make sure your mouth isn't *too* close or *too* far away from the microphone when recording.
"Point the top of the microphone directly at the front of your mouth, holding it one or two inches away and just under the lips. Don't touch the microphone "windscreen" with your lips, or hold the microphone to one side of your mouth. " Source of information and picture representation
Here.
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Are there particular file formats you'd prefer? Size limitations? Anything else which temporarily escapes me?
Mp3 or Wav are the easiest to work with, at least they were for me. As for other specs:
No size limit unless Mumbling wants to enforce one
Sampling rate: please use 44100Hz (44.1kHz) or higher. The result will likely be downsampled to 44.1kHz (though this is entirely Mumbling's choice. I used 44.1kHz because my virtual instruments are all 44.1kHz) so recording higher will just waste space for the sake of this project (pros would argue that recording higher is better but for the sake of this, I don't see a point.)
Mono preferred. Stereo just wastes space unless you're actually recording with 2 microphones in a stereo configuration.
I'll let Mumbling make the final calls though. She's in charge now. B) I'm just a backseat driver.
