I understand the value of reading source code, and I am trying my best to read as much as I can. However, every time I try getting into a 'large' (i.e. complete) project of sorts, I am overwhelmed.

For example, I use Anki a lot when revising languages. Also, I'm interested in getting to know how an audio player works (because I have some project ideas), hence quodlibet on Google Code.

But whenever I open the source code folders for the above programs, there are just so many files that I don't know where or what to begin with. I think that I should start with files marked init.py but I can't see the logical structure of the programs, or what reasoning was applied when the original writer divided his modules the way he did.

Hence, my questions:

1. How/where should I begin reading source? Any general tips or ideas?
2. How does a programmer keep in mind the overall structure and logic of the program, especially for large projects, and is it common not to document that structure?
3. As an open source reader, must I look through all of the code and get a bird's eye view of the code and libraries, before even being able to proceed?
4. Would an IDE like Eclipse SDK (with PyDev) help with code-reading?

Thanks for the help; I really appreciate your helping me.