Hmm, wonder if the best option is to just go with a single nice piece for the menu and game start, then leave in small teasers for other pieces at most and just make a really obvious option in the menu to enable the full music package? In addition of course to a "full" download package in the first place.
As for Git & GitHub, you primarily need just one step and it has a very nice guided hosted on GitHub:
http://help.github.com/win-set-up-git/
(I suggest using "Run Git from the Windows Command Prompt" for Windows)
So if you sign up for GitHub, install Git, and do the SSH key step (probably the most scary) you're almost done. For work-in-progress and samples you could use the new TeraMisc repo directly (no need to fork) and likely use plain ole simple command line (no need for IDE - tho maybe there are some nice Git utilities for simply managing a few files). That would go something like this:
1) Clone the target repo (easy enough, can provide the exact command) into a work directory - one time
2) Put files in the work directory or just actually work in that directory
3) Use "git add" to mark new/modified files for commits when ready
4) Commit command!
5) Push command!
A nice benefit from that is having different editions readily available, nice activity flow from GitHub, and the files would be in the exact spot we could make the game's "music downloader" grab them from, no code change needed for edition updates
An added side benefit is that it would then be easy going from that to a full DevSetup later for when we have a more friendly audio & music pluggable system you could tinker with sfx in-game on your own to get a better feel for things