In my opinion overpopulation is not overstated - but I appreciate the fact that different people who have the same information come to different conclusions. That's what makes discussions interesting. :)
I come to my conclusion when I think about how fast we exploit the limited resources available (the amount of clean water, the number of edible fishes in the oceans, the rain forests - nearly all important resources are decreasing). Yes, we may find new ways ... start to eat insects, farmed algae or artificial food from cell cultures for example, but finally the resources are limited and we are getting more and more.
Your idea to conquer the universe is really fascinating, but considering the enormous distances I have some doubts if it will come true (and if it will be done successfully). We (or better to say our descendants) will see.
By the way, if I was god (not that I am sure that there does exist one) or whoever who constructed the universe for whatever purpose I also would have made we distances as huge as they are to make sure that such an aggressive species like Homo sapiens stays restricted to a very limited area. :-)
RE: Human immortality?