The first line is clearly humorous, saying, "watch out not to look down on one of these little ones." But obviously, because they are little, we have to look down on them.
Jesus did not use the word "angels," but the Greek source of that word that means "messengers," often in the sense of how the Divine inspires our thoughts. So the sense is that children are in closer communication with the Divine.
The words translated as "do always," or "always" doesn't mean that. The phrase is "though all" in the sense of through all the illusions of the world" they see God's face.
Christ's Words in Matthew as a Guide to 40 Days of Prayer.