Is it permissible to pray behind an imam in a mosque where the Qur’an is recited in congregation before the Adhan and before the khatib ascends, and where people are reminded of two hadiths about idle talk when he ascends?

Reading the Quran collectively before the Friday sermon and regularly reading two Hadiths after the Khatib sits down are innovations (Bid'ah) because there is no legitimate religious evidence for them. However, prayer in a mosque where this occurs is valid, but it is preferable to move to another mosque where none of this takes place.