I wasn't going to post anywhere but on the DNA questions thread but this one is just too tempting, even though I'm pretty sure I'll only get unwelcome responses. Oh well.
I just think your questions are awfully intelligent. You really think about these things. So did I before I became a Christian. I strongly felt that life is meaningless, pointless, and I looked for meaning and found none. Not that I couldn't find plenty to occupy me pleasantly and productively in my little rut, but the question is, as you know, much bigger than that, and the happiness of the rut often serves only to blind us to the bigger picture.
I can't help but make this a gospel message I suppose although I'd like just to state the simple fact that when I became a believer I DID find meaning. I was NOT looking for God, I knew nothing about the gospel at all, nobody preached to me, or if they did I didn't hear it, tuned it out. It came up behind me and hit me on the head as it were. Through books. I read my way to belief in the God of the Bible over a period of a few years. I didn't join a church until years later. It took a while for the message of salvation to sink in: Salvation? Saved from what? Etc. etc. etc. I had a lot to learn. But the learning was immense joy.
About the "meaning of life," which is what you're asking about, the line from the hymn "Oh Holy Night" has always said it for me and it can still make me cry: "Then He appeared and the soul knew its worth." The soul knew its worth. If all we are is chemicals thrown up by mindless mechanical laws how can we have any worth? All the productive or pleasurable things we do, good deeds or whatever, give us no worth if we're just going to return to dust at the end of it all. That's what the question is about, isn't it? But now I know that the human soul has worth. All human souls. I wish all of you knew that.
So back to the DNA thread.
He who surrenders the first page of his Bible surrenders all. --John William Burgon, Inspiration and Interpretation, Sermon II.