Hmm... perhaps I'm dull, but I thought that Darrow and Tipler had
built up a fairly convincing explanatory answer to these questions
in their book THE ANTHROPIC COSMOLOGICAL PRINCIPLE. I mean, it may
not be very satisfying to learn that these things are the way they
are because of a selection effect (I think the Anthropic Principle
dovetails quite beautifully with the Many Worlds interpretation,
though), but even if I wasn't rock-bottom convinced (and I wasn't),
these questions became far less interesting to me after I had read
the book.
(There's also a neat little chart on the web, pointed out here
recently by Steve Witham, at http://www.sns.ias.edu/~max/toe.html
that makes things a bit more concrete. "The figure below illustrates
how little one needs to change some aspects of our world to make
it hostile to life...")
(Note: just because I like the Anthropic Principle doesn't mean I
entirely approve of Tipler's more recent plucking at Tommaso Aquino's
laurels. I can't imagine why Tipler's going into competition with
a rationalizer of witchburning.)
-- Eric Watt Forste ++ Q: What is the meaning of life? ++ A: You're soaking in it!