big-picture question regarding Lilypond's capabilities (current and potential)

[Kieren MacMillan]

Hello all,

My two-act musical, "Robin Hood: The Legendary Musical Comedy", had a 
three-week run at Toronto's Hart House Theatre in January. It was quite 
successful, to the point that several parties have voiced an interest in 
further developing and producing it.

In my dream world, people who are interested in producing any of my musicals 
should be able to say (e.g.) the following:

    1. “I would like PDFs for the full score, vocal score, vocal book, and band 
parts for piano+bass+percussion."
    2. "I would like ‘Generosity’ transposed down a tone.”
    3. “In the opening number, I would like to cut mm. 101-117, and have mm. 
212-213 made into a vamp (i.e., with repeat signs and the word ‘vamp, cont. on 
vox’ written above).”

This email is to determine to what degree these are possible now, or might be 
possible in the future.

In particular, I'm interested in #3, since it could more seriously impact the 
way I organize the input code. (For #1 and #2, it's mostly just figuring out 
and perfecting the infrastructure for on-demand printing — nontrivial, to be 
sure, but mostly post-input-code.)

Given the current (v2.17) capabilities of Lilypond, what are the various ways I 
could accomplish #3?
What's likely the "best" way?
Are functions like \partCombine, \extractMusic, etc. up to the task(s)?

Thanks,
Kieren.