Salat (Prayer)

Reciting from a Copy of the Qur’an (Mushaf) in Tarawih and other Prayers

My question is regarding the recitation of the Qur’an while looking at the text during salah. I was reading a book and in it, it says that reading the Qur’an while looking at the text in salaah breaks the prayer. Is this true or are there certain circumstances when it is permissible? Is this permissible in Nafl or Tarawih prayers? Can the Imam lead Tarawih whilst reading from a copy of the Qur’an and can we follow such an Imam? If a person is say praying Qiyamul Layl and wants to read sections...