The biggest take away for me was the recap of the Apostleship
The apostles were sovereignly selected by the Holy Spirit, I Cor. 12:11; Eph. 4:11; and I Cor. 12:28. "All these are the work of one and the same Spirit, and he gives them to each one, just as he determines." (I Cor. 12:11) "It was he who gave some to be apostles, some to be prophets, some to be evangelists, and some to be pastor/teachers." (Eph. 4:11)
The gift of apostleship was the gift of absolute (over all the churches) spiritual authority. The gift was to sustain the Church until the Canon of Scripture was completed; and this completion occurred in 96 AD. And the exercise of absolute spiritual authority requires the spiritual gift.
The apostles to the Church were not appointed until after the resurrection of our Lord, Ephesians 4:8. "This is why it says: When he ascended on high, he led captives in his train and gave gifts to men."
Thus, it is necessary to distinguish between the apostles to the Church and the apostles to Israel. The apostles to Israel are cited in Matthew 10:2-10. There is, however, an overlap between the two groups in that eleven of the apostles to Israel became apostles to the Church.
Acts 1:22, I Cor. 9:1, and 15:8,9 state that the apostles to the Church were required to have seen the resurrected Christ. Whereas the apostles to Israel beheld our Lord in His Incarnation (human body prior to the Cross).
The spiritual authority of the apostles was maintained, confirmed and validated by supernatural gifts: the gifts of tongues, miracles, and healing, according to Acts 5:15, 16:16-18, 28:8,9.
The catalogue of the apostles to the Church: Simon Peter, Andrew, John, Philip, James, Bartholomew (Nathanael), Thomas, Matthew, Simon Zelotes, Jude (Thaddeus, Lebbaeus), James (the Less), and Paul. Note that Paul replaced Judas Iscariot, according to I Timothy 1:12-16 and I Cor. 15:7-10. The election of Matthias in Acts 1 was illicit; God the Holy Spirit reserves the right of appointment.
According to Acts 14:14, Barnabas was also an apostle. And the fact that James (the Less), our Lord's half-brother, was an apostle is confirmed in I Cor. 15:7, and Galatians 1:19.
And there were, possibly, two other apostles: Apollos, in I Cor. 4:6,9; and Timothy, in I Thessalonians 1:1, 2:6. Additionally, Sylvanus (Silas) is identified with Timothy but not necessarily as an apostle.