Minecraft – How to easily find an Ice Plains Spikes

Sheep spawn on any difficulty, and on any setting. They do however require at least 2 blocks of grass, not dirt, in a 10x10 area of grass, and sunlight. They will only spawn during daytime. By default, every 80 seconds the server will throw a dice to see if, and how many creatures will spawn. This can be sheep, pigs, chickens or anything like it.

There are two village centers to consider here; one on creation, and the one you actually care about.

On world generation, the village's well is considered the center (or starting point) of the village. It is the first structure placed, and the entire village construction is based upon the well's location.

The center of the village you actually care about is the centroid of all the doors in the immediate vicinity. If you took all the coordinates of all the doors in your village and averaged them together, this would be the area where golems would spawn.

For additional details on the logic of the center of the village, read this section in the Minecraft Wiki.