First of all, there is no "Protestantism church". Second, the authority is God, through The Bible. The typical Protestant church has a group of elders who watch over and lead the church, some of whom are also pastors who teach the congregation. These elders answer to God still, and should only deliver the message of God as it comes from the Bible.
Yes. They are under the authority of Patriarchs.
yes they did
Leo
The counter reformation
Gregory the Great
Yes he did, he was the starter of Protestanism.
The pope is the leader of the entire Christian Church. However, only Catholics recognize this authority.
St. Peter is given the "keys to the kingdom of Heaven" by Jesus, which symbolizes his authority as the leader of the Christian church. This is referenced in the Bible in the Gospel of Matthew 16:18-19.
The pope in Rome is not the leader of any Orthodox Church. The pope is only the leader of the Roman Catholics and has no jurisdiction (power or authority) over the Orthodox Church, which has its own leaders, such as the Ecumenical Patriarch in Constantinople.
it supported it because they led to new creations that helped the church and its people
If you are referring to the Baptist church, there are many leaders. There are so many subgroups of Baptists you can't really pin down one particular church leader as an authority for all of them.
Magisterium is the teaching authority of the Church.