Reading Bill Bryson's tour de force "A Short History of Nearly Everything" gave me some additional insights (see the early chapters).
And a few days ago I came across this link at Yahoo! Canada and the following article at www.space.com which I found especially informative on this matter:
Universe Measured: We're 156 Billion Light-years Wide!In particular, it neatly outlines one aspect that beforehand I simply couldn't get me head around: why, if the universe is some 13 or 14 billion years old, its diameter in light years can be numerically greater than this. And it turns out that the above figure -- converted, of course, into distance in Light Year units -- cannot simplistically be regarded as the radius which, by being doubled, would lead to a diameter of 27 or 28 billion light years. And the key to this is explained thus:
If you've ever wondered how big the universe is, you're not alone. Astronomers have long pondered this, too, and they've had a hard time figuring it out. Now an estimate has been made, and its a whopper. The universe is at least 156 billion light-years wide.
... the universe has been expanding ever since the beginning of time, when theorists believe it all sprang forth from an infinitely dense point in a Big Bang.
"All the distance covered by the light in the early universe gets increased by the expansion of the universe," explains Neil Cornish, an astrophysicist at Montana State University. "Think of it like compound interest."