Pokemon-go – Pokemon go and eggs not hatching

Eggs come in three distances: 2km (1.2mi), 5km (3.1mi), and 10km (6.2mi). The distribution of these seems to be relatively random, however 5km seems to be somewhat more common than the others. 10km seems to be somewhat rarer for now, however these numbers have become extremely balanced since the beta.

Pokemon's strength (and rarity) is usually determined by the distance you need to walk to hatch the Egg.

You can get any non-legendary (and egg-grouped Pokemon) from eggs, although some are rarer than others. For instance, you're much more likely to get a Rattata than a Growlithe from an egg.

They are placed in order. so the last ones are the oldest. But the CP is determined once you hatch them, not when obtained. so it doesnt matter which you choose to hatch.