A couple of thoughts on this.
First, I don't think evolutionary trait and social construct is an either-or. Social constructs can be the subject of selection, just as genetic traits can be. The real question is whether the trait is heritable. A social construct can be heritable, and if it is, then it can be under selection pressure.
Second, I agree with you, Crpapjda, that there are strong parallels between the evolutionary answer to the problem of altruism and the evolutionary answer to the problems of many of the kinks that we're talking about here (including, maybe most interestingly, male homosexuality).
Third, I'm not sure I agree with you that societies "evolve" in the sense that you seem to be using the word in your point 2. If you mean (as I think you do) that societies "advance" in context of evolution, I think that, too, is a discarded notion. It is the case that societies advance in a technological sense. And the speed of change is clearly accelerating. However, I think societies, like populations, are "fit for purpose". That is, they are well suited to the environment. As the environment changes, populations (and maybe societies) change (i.e., "evolve") in response to those environmental changes. But I don't think it's fair to characterize a latter iteration of a population (or a society) as more or less "advanced". They've just changed in response to a changing environment.
I have got to get this survey posted so that we're not talking into the ether, but have a real work in progress to discuss (and work on). I'll get cracking....