2. Is pointless. Both the labor pool and consumer demand scale with population. If you halve the population then you halve the number of jobs required to meet demand, and overall unemployment doesn't actually shift that much.
You don't need to incentivise, anyway. There's a consistent pattern that happens in all countries as they develop: First there is a long, long period of steady population, in which short live expectancy and high infant mortality balance a high birth rate. That's the bit where every family has six children. Then there's an explosive population growth when industrial agriculture, sanitation and medicine come along: You still have the big families, but now people aren't dying any more and population shots up, more than doubling in a generation easily. Then a remarkable thing happens: The birth rate falls. Higher educational standards and sex equality serve to discourage people from wanting children until much later in life, and contraception gives them the option. Population can actually start to fall. This creates its own problems, like an overburdened health system.
Some countries have had to resort to coercive population control during the explosive growth period, but even China is phasing out their population control efforts now - they recognise that their need has passed.