opinions of mine follow and do not necessarily represent the perspectives of the christian broadcasting network
The first thing God commands his newly created humans in the Torah is, "Be fruitful and multiply."
The creation of humans is described twice and in two ways. There are books written on this, some authors believing that this is intended to describe either two aspects of humans or two kinds of humans or two layers etc.
It is my understanding that the difference in Genesis between people and beasts is our moral understanding. The second creation may refer to that. I'm not the last word on what it refers to.
Every creature is 'Commanded' to reproduce despite the fact that some cannot. For example sometimes people are infertile, so they can't do this. How can the command be intended to cover all circumstances? I think it is more like a description of the way things work, and in that sense only it is a command. The meaning of the word 'Torah' as I understand it is flexible enough to allow this usage. Math is a kind of Torah. In other words it could be less of a command and more like a manual or guideline. Reproduction has a purpose in other words, but since the creation of humans is described twice many infer there is more to this purpose for humans than there is for other creatures in the garden. Possible also the command is not simply to reproduce period but to reproduce good children, implying that moral quality matters.
Sometimes the NT writers refer to spiritual fruit, and by doing so they interpret Genesis to mean that reproduction may be spiritual. Example: If you influence others to become peacemakers then you're reproducing spiritually.
Do you believe procreation is a moral imperative for us as human beings?
Sometimes it is. Its when the world seems terrible that people are afraid to have children, but isn't that the time when good people ought to make children? It is sometimes an act requiring courage. Other times its not. How you rear children matters, too. If you're training them to be cruel then there's nothing moral about how many you have. To me this implies that if you have no clue how to rear children and just want them for someone to do your chores then maybe its not such a bad idea to wait...however this is not what Genesis implies.
Noah's parents according to the story only have him in order to have someone to do their chores, yet he turns out to be very important. Hmmm.
Is it an imperative for each of us as individuals, or just broadly as a species? If it's a moral imperative for our species, at what point does that responsibility become individual?
Individually. I think you weigh up what kind of offspring you'll have and make a good decision. For example if you have genes which produce madness, then maybe its not a good idea to reproduce. I think that the individual bears some responsibility for having children with at least the potential to be morally strong.
If a person chooses never to procreate, have they sinned? If a society does not procreate enough to replace themselves (as we see with a number of Western countries), are they morally failing as a group?
They have not necessarily sinned, but I think they should follow their conscience in the matter. Perhaps adoption is better, or perhaps its better if they don't go near children. It depends on the person, their ability, their failings. Do they have enough help? Is the kid going to be left in a cage all day?