Short answers, pulled from the story.
Most experts agree that seven letters were written by Paul himself, including Galatians and Romans. These texts date from approximately 48 AD to 57 AD based on historical analysis of their content.
Scholars have divided the thirteen books attributed to Paul the Apostle into three distinct groups since the 16th century. This division creates a complex landscape where only half the collection commands universal agreement among historians.
Paul explicitly stated in multiple epistles that he utilized secretaries to draft his correspondence. Joseph Barber Lightfoot noted that Paul sometimes took the pen from his amanuensis to write concluding paragraphs with his own hand in large bold characters.
The Epistle to Hebrews stands apart because it does not name Paul as its author despite traditional claims. Modern scholarship almost universally rejects Pauline authorship for Hebrews due to stylistic differences.
Modern editions place the Pauline epistles between Acts of the Apostles and catholic epistles while most Greek manuscripts arrange general epistles first. Jerome popularized placing Hebrews at the end of Paul's letters through the 4th century Vulgate translation.