"I never do songs with my group of 10-year-olds. They think singing songs is for babies." - I personally disagree with this statement since I trully believe that by singing song people of all ages would be able to recall info later on just by remembering the rhythm.
"I always start the lesson with a review of the previous lesson. And I always end the lesson with a song." - I agree with this statement. Establishing sort of a routine helps learners to move from one stage to the other with no difficulty and allows the class to have a certain "flow". To be familiar with the lesson is a great advantage for young learners.
"I prepare extra exercises for the children who finish early. It's not good if they have nothing to do." I agree to a certain extent. It all depends on the children, and how keen he is on learning because they may see it as unfair and will claim something like: Why do I have to work more than the others?