Is it permissible for an Imam to play Al-Burda poem and religious songs instead of the Quran before the prayer, and to ask the people to hold a gathering of remembrance (dhikr) that includes sending blessings upon the Prophet and reciting the Shahada 100 times each through the mosque's microphone after the Isha prayer, or is this considered an innovation (bid'ah)?

Muslims must adhere to the Sunnah (definition) of the Prophet and beware of contradicting it or introducing innovations (bid'ah). Among the reprehensible innovations are: broadcasting the Qur'an aloud before Friday prayers, playing religious songs that may contain exaggeration or contradict Islamic law, such as the poem of Al-Burdah, and collective remembrance (dhikr) in a single voice in a manner not reported from the Prophet, peace and blessings be upon him, nor from his companions.