Was the ministry of the twelve apostles Jewish or was it part of the new church age?

The ministry of the twelve apostles was Jewish, not part of the new church age. Their Gospel of the Kingdom remained basically Jewish, tied to Temple worship, Old Testament covenants, and the promised Messiah. It required repentance, baptism, and belief that Jesus was the Christ, while the blood of Christ and the Pauline revelations belong to the new church age.

Les explains that Apollos was instructed in the way of the Lord, knowing only the baptism of John. He knew nothing of Paul's Gospel; he only knew the Gospel of the Kingdom preached by Jesus in the twelve and John the Baptist. Les says that Gospel was still basically Jewish—connected with Temple worship, the Old Testament covenants, and the promise of the coming Messiah. The four Gospels belong to the Old Testament, where the blood of animals was the only approach to God. The blood of Christ is the way to God once we get to the Pauline revelations. So the twelve's ministry was Jewish, not the new church age. Later, Priscilla and Aquila expounded unto Apollos the way of God more perfectly.

Was the church of the twelve apostles Jewish or Gentile in its orientation?

The church of the twelve apostles was Jewish in its orientation. The Gospel of the Kingdom preached by Jesus in the twelve was still basically Jewish, connected with Temple worship, the Old Testament covenants, and the promise of the coming Messiah. It was not yet the Pauline revelation to the Gentiles.