Surely you are not implying that none of the other Apostles preached the word to any non-Jews are you? There is way too much Scriptural and historical evidence to the contrary.
The point of the ministries of all of the Apostles, St. Paul included, was to eliminate the differences between Jew and Gentile, not to institutionalize and perpetuate them.
Not initially...Not til after the Jews rejected their Messiah and killed him...It wasn't revealed to Peter by Jesus for some time after Jesus was killed...
Initially in the ministry of Jesus, there was a huge difference between Jew and Gentile...
Eventually the point was to bring all to the knowledge of the saving grace of Jesus Christ, WHERE there is no difference between Jew and Gentile, in Christ...And that was to make the Jews, God's chosen, jealous of the Gentiles, to provoke them (the Jews) to come to him...