I desagree with the first statement. I find that children at any age enjoy singing. Songs are a good way of aquire grammar and vocabulary, if you show the lyrics. It will also help in improving spelling. Songs that are popular make students wanting to listen over and over practicing pronunciation and intonation.
Having a routine during classes, provides students comfort thinking that they have the control by knowing what is next. it also decrease the anxiety making students relax and focus on learning.
I believe it is important to have extra activities for children who finish early. the extra work could be to practice vocabulary from other units, review using puzzles, crosswords or even asking them to help other students.