Introduction: My main focus with students is to get them to the point where they can read, play and write music.
For composing music, I prefer this be done through online resources which requires a minimal monthly membership fee (comparable to Netflix).
The song lists for beginners (younger students) will follow a standard curriculum with classical, traditional and popular songs. Once the student has been able to grasp a better understanding of the piano and reading, they will progress to a more classical-based repertoire. However, I do think it is very important to give the student additional options for song choices he or she is interested in learning. This will help to keep the student interested, engaged and motivated.
In regards to younger students, my personal belief is that the piano-learning process is a joint effort, evolving both the student and the student's parent(s)/legal guardian(s); there may need to be coaching to ensure that the younger student practices daily in order to reap the full benefits.