Those look like a good resource. I wouldn't really know where to begin, were I a parent, as far as what a child at a given level should be able to do.
As a language educator, we have benchmarks for what language learners should be able to do, linguistically, at any given point in their development. Raising a child has got to be much more difficult, though!
Yes, it's a pretty interesting book. I'm glad I picked them up because they have a lot of info in them. I thought they were just going to be full of lists like, "You kid should know this or that..." but they actually contain the poems, songs, lessons in the book. Pretty nice!