Plenty of research done by that other hc favourite, the United Nations. Iran is an interesting example. The Wiki link I gave finishes with a paragraph on how President Ahmadinejad wants to double Iran's population in short order by making Iranian women the obedient uneducated baby machines of old.
Starbust
You asked:
"What do we do with the existing billions that want to put extra demands on our limited resources?"
Beyond foreign aid, education, access to contraception, and the uncertainty of what technology delivers, not much. But imo much of the technology to replace fossil fuels has most to offer them,
