1. Is it obligatory to recite Surat Al-Fatihah behind the Imam? 2. What was the manner of the Tarawih prayer performed by the Messenger of Allah, may Allah's peace and blessings be upon him, and did he glorify or recite specific supplications collectively after finishing it?

The view of the majority of scholars is that the congregant (ma'mum) should not recite behind the Imam in a loud prayer if they can hear his recitation, due to the Almighty Allah's saying: "And when the Qur’an is recited, then listen to it and pay attention that you may receive mercy" (Quran 7:204), and the Prophet's (peace be upon him) saying: "Indeed, the Imam is appointed to be followed. So when he says 'Allahu Akbar,' then say 'Allahu Akbar,' and when he recites, then listen attentively."

As for Tarawih prayer, its origin is the action of the Prophet (peace be upon him), who prayed it for several nights out of fear that it might become obligatory upon the Ummah. Then, Umar ibn al-Khattab gathered the people behind a single Imam, Ubayy ibn Ka'b. The Prophet (peace be upon him) used to pray it eleven rak'ahs, prolonging the standing, bowing, and prostration. The Companions continued this practice.

There is no harm in increasing beyond eleven rak'ahs, due to the Prophet's (peace be upon him) saying: "Night prayer is two by two." However, communal tasbeeh or specific dhikr after Tarawih has no legal evidence (from the Sharia) supporting it.