Is it permissible to stop praying in a mosque whose Imam believes that the Sunnah prayer before Jumu'ah is obligatory and practices other innovations such as vocalizing Dhikr, using the tambourine, shaking hands after prayer, and praying in congregation with family at home?

The preponderant opinion is that Jumu'ah prayer does not have a pre-prayer sunnah (regular supererogatory prayer). However, if a worshipper enters the mosque before the prayer, he should not sit down before praying Tahiyyat al-Masjid (the two rak'ahs for greeting the mosque). He may pray as much as he wishes, or engage in dhikr (remembrance of Allah), or recitation [of Qur'an] until the khutbah (sermon) begins. It is not permissible for someone who believes that Jumu'ah has a pre-prayer sunnah to compel others to adopt this view. However, if innovations (bid'ah) are found in the mosque, they must be denounced by hand or tongue; otherwise, by the heart. And do not refrain from congregational prayer unless you find another congregation where innovations are not practiced.