Kaa was born in Rangitukia and was educated at Te Aute College. He obtained his L.Th. in 1932 at St John’s College. In 1935 he married Maharata Flora Richards and had a family of twelve children of whom seven survived. He continued his education at Auckland and Victoria Universities and graduated with a B.A. majoring in Hebrew and Greek in 1951. Kaa worked as an Anglican minister in Tokomaru, Porangahau, and Waipatu (Hastings) pastorates and worked in the Waiapu Diocese as Vicar of Taupo, Waipawa Māori Pastorate and Vicar of Moteo. In 1962 Kaa was licensed by the Dean of Christchurch to work amongst Māori in the Christchurch Diocese. Kaa was made a Canon of St Johns Cathedral in Napier in the 1950s. Kaa was a recognised authority on te reo Māori and was part of the Māori Bible Revision Committee. Kaa translated directly from the Hebrew and Greek into the Māori text and was one of the rare scholars of the period who could do so. He was also a member of the Māori Dictionary revision committee. Kaa was a prolific writer and wrote proficiently in both Māori and English. He critiqued Tutira: New Zealand Station written by W. H. Guthrie-Smith and was a consultant for John Grace’s Tuwharetoa. Kaa wrote submissions to synod for the Māori Ecumenical Council of Churches and was often called upon because of his literary skill. A lot of his early writing in te reo Māori was destroyed in a fire in 1950. Kaa was a foundation member of the Māori section of the National Council of Churches.
- Phone conversation with Kuni Jenkins, 4 Sept 1998.
- Te Ao Hou 41 (1962): 8.
- Te Ao Hou 51 (1965): 63-64.
- "Race Relationships." Te Ao Hou 8 (1954): 42-43.
- In this discussion of human equality written in Māori and English, Kaa freely acknowledges that ‘no two human beings are equal’. However, he argues that there should be equality in terms of consideration and regard, and of ‘opportunity for developing innate capacity and latent worth’.
- "Visit to Indonesia." Te Ao Hou 37 (1961): 40-44, 49.
- Kaa gives an account in Māori and English of his trip to Indonesia in April 1960 when he went to assess the spread of Christianity in that nation. He provides a general background to Indonesia and its people and discusses their languages, religious beliefs and the thriving state of the Christian church.
- "Haere Ki O Koutou Tipuna." Te Ao Hou 51 (1965): 63-64.