12 apostles

Does Paul/Saul make Apostle #13, or is he somehow 'part' of the twelve? Regarding the two James, is one of them the brother of Jesus?? Is James son of Alpaeus also the son of Clopus? Or is that an entirely different James? Is Thaddaeus the son of one of the James'?? Is Barnabas(Paul's sponsor)...

I found that the period of Christian history following the end of the book of Acts was one of the most important that I was unfamiliar with. I was familiar with the story of the gospels and the events of Acts, but not with the apostles' missions outside of what was narrated. Revelation is a...