Not my type of writing, but if I were to write something that required this kind of extensive backwork, here is what I would do:
1) Carry a notebook and pencil with you at all times. (In my opinion the perfect notebook is the
Moleskine Reporter. Do ignore the hype about all the big names who "preferred Moleskines" -- it's just a notebook.)
2)
Use the notebook. Don't just keep it in your pocket. Jot down ideas -- no matter how half-arsed, turns of phrase, pieces of overheard dialogue (and phone-numbers, to-do lists and other non-writing related stuff too.)
3) Install a local web-server on your computer and set up your own personal Wiki on it. Wikis are great for semi-structured information and ideas; you can structure things out when you've got the time or just quickly copy ideas from your notebook into it if you've only got five minutes. You can cross-link and cross-index the information easily, link to external sources on the internet, add photos and diagrams, change it at will and search the entire site. Most importantly, you have
everything in one place (Well, two if you include the notebook; but you should copy everything from the notebook to the Wiki at least once every week.)
There are custom-made software that's designed for keeping track of ideas and "creative information" of this ilk, but Wikis are free and quick to both learn and use, and does the job well enough for most people.
