How to start with Composer internals?

I've just looked at Composer, and my interest has been piqued by the 
thought that it is very close to offering the abilities of a true, 
general-purpose editor--and perhaps some abilities beyond that. So I'm 
interested in perhaps learning about and contributing to the Composer 
code base. I'm hoping for answers to a few questions that might get me 
off to a fast start.

1) How active is the Compose project?
2) What language(s) is Composer implemented in? Is it all C/C++, or is 
there a higher-level scripting interface also available? I don't suppose 
there's a Python wrapper?...
3) Is there a home page for the Composer project, separate from SeaMonkey?
4) Do I need to check out all of the SeaMonkey source to compile and 
program Composer, or can it be checked out as a more self-contained project?
5) What's the best way to start learning the internals? Just check out 
the source, is there a better way?

Thanks,
Ken