Hi, Kay —
There are many, many more than five infallible doctrines in the Church. For help I'd consult the book Fundamentals of Catholic Dogma by Ludwig Ott. (TAN Books)
[Hard cover from TAN|Used Soft cover|On Amazon]
The authority of bishops, including the Pope, is limited in that they cannot define anything which contradicts what has been infallibly defined before, or is inconsistent with Apostolic Tradition.
Bishops, individually, cannot define anything new as infallible, but in council and in union in the Pope and each other, they can. Also, they cannot define anything that is not a matter of faith or morals.
The job of the Pope and bishops is to guard and clarify the teaching of the Apostles. They cannot go beyond that deposit of faith entrusted to the Apostles, but they do have the authority, through the Holy Spirit, to interpret the deposit of faith and set boundaries on our understanding of it.
Of course, all are bound by God's law, but no human power can judge the Pope.