Dan01 - 7:48 am on Sep 1, 2011 (gmt 0)
Wow Tangor. Thanks. Those are mysteries to me too (1 and 2).
As per my second question - I don't think Google crawls the whole site in one crawl. I would assume that they crawl part of it, take a note where they left off, and then come back and crawl some more the next day (or later depending how often content is updated).
Also, as per #3 - you are right. I have been less likely to delete an article if it pertains to high-paying keyword.
Again, your answers were great.