Minecraft – Can you spawn special villagers

You will need to return at least 2 villagers. Then they will start repopulating the village. As of 1.2, villagers will mate and repopulate based on the number of available houses. See this post (especially the "your village died out" section) for more information.

As of the 1.8 snapshots, though, the villagers need to be "willing" to breed in order to breed. It seems that you can make a villager "willing" by trading with them. Willingness is granted on the first new trade offer, and at a 1 in 5 chance per subsequent trade. Once a villager is willing, they will immediately seek another willing mate, if the village can sustain more villagers (based on the number of houses).

Essentially, infinite.

The value of 32 blocks determines how far away from an existing village a villager must be to create a new village. Hence, if you build a load of village structures 32 blocks apart, you will have saturated the land with villages. Then, just expand from your 'nodes' to create a village around each one. From the villagers' perspective, there will be a separate village every 32 blocks, but from the players' they'll all appear to be the same.

So by 'Essentially infinite' I meant you can create a continuous village-scape that will be populated with villagers, and each actual village therein will be ~64x64.