The Holy spirit teaches all that are spirit filled. He is the teacher of all spirit filled believers, regardless of what your status is. An apostle is one who has been chosen by God, separated from the others to solely preach and teach the gospel of God. That is his only task. Paul's apostleship was solely to preach the gospel to the gentiles. even though he was an israelite, he was called to go to the gentiles. The other apostles had task of preaching to the Jews, the romans, the Hebrews and others.