Keywords and indexing in Bridge CS-3

I decided this afternoon that I'd sift through a USB hard drive, the one that contains all my 2008 pictures, and select the better photos for printing to a promotion book. Normally I would do this by scrolling through folder after folder in Bridge, then copying the selected files into a new folder somewhere else. But today I thought, "Aha! Why not take advantage of those Keyword/Collections/Search capabilities and use the program the way it's supposed to be used: tag the winners with the Keyword "portfolio", then compile them, or their surrogates, in a Collection. Nothing to it, right?

Well, it's easy enough to tag the files with the Keyword, but then I get into trouble. If I use the "Find" function, Bridge will only report on, maybe, half of my choices. Run Find again with "Include Non-Indexed Files" and the process takes hours, assuming Bridge doesn't crash before it's finished. Even if I make it through all that, I then have to wonder whether Bridge is reporting ALL the relevant files to me.

So I have a lot of questions.
[blockquote]Why is there almost no mention of the word "Index" in the Bridge documentation? Am I to assume it means the same as "Cache", both as a noun and a verb?
How do I "Index" a folder or drive? Bridge appears to be doing that for me when it's searching "non-indexed" folders, but if I initiate a new search, it starts all over again.
Is the Index connected with the Centralized Cache?
How do I tell if a folder is indexed or not?
If I have to purge the cache, will that kill my indexing? Even if my exported caches in their folders stay intact?[/blockquote]

In short, am I just wasting my time trying to use Bridge as a cataloging tool, even in the small way that I am?

Thanks. MB

Photoshop CS-3
Windows Vista 64bit
Core Duo 8800 (I think)
8 GB RAM
500 GB C: drive, about half full
1 TB USB hard drive, about half full