According to the Catholic Church, he’s not sinless and may confess to the priest of his choosing. He is (regarded as) infallible in matters of Catholic doctrine, but I believe that’s the extent of his perfection.

Generally the Pope is considered to be on such a high level spiritually that he deals directly with God. However, historically, during the Great Schism in the late Middle Ages, the Council of Constance established that the body of Christ was greater than the leadership, and if the church leadership were incapable of leading the church (i.e., two popes resulted, etc.), then a council representing the body of the Church could be established. Should the Pope be in need of any major confession or penance, then doctrinally, he would have to answer to a church council of some sort.