Actually from what I understand of the scriptures, all the Suttas are considered to be in the handful of leaves. There are the Suttas, the Monks' rules, and the Abhidhamma. Usually the Suttas are considered to be in the handful of leaves. But we don't have to know all of them, because this is a collection of all the Buddha's teachings, and he gave different teachings to people at all different levels at different times. So he wasn't giving them all to one person.
If you understand the Four Noble Truths and that the Noble Eightfold Path is part of the Four Noble Truths, then we have a good foundation for practice. The Satipattana Sutta describes Right Mindfulness basically. Right Effort, the Four Great Efforts, that's also within the Noble Eightfold Path. So if we have a little bit more detailed understanding of the Noble Eightfold Path it's very helpful. The Mahacattarisaka Sutta is a very good one for describing the Noble Eightfold Path and how Right View comes first.