The words "these things" probably refers to truths. Alternate translation: "you hid these truths from ... and revealed them to" or "you have not made these things known to ... and you made them known to"
"people who are wise and understanding." Jesus said this because some people thought they were wise. Alternate translation: "people who think they are wise and understanding"
"to people who are like little children." Jesus is emphasizing that many of those who believe him either are not well educated or do not think of themselves as wise.