If you look at Titus you will find that Paul uses the term elder and bishop interchangeably and says he appointed Titus as an elder to Crete. The only laying on of hands that Paul received was from prophets and teachers at Antioch, not Apostles or bishops, along with Barnabas. Was Paul a bishop or not?
Paul in Ephesians sets out the offices given to the church to equip the saints for the work of the ministry. They are Apostle, Prophet, Evangelist and Pastor/Teacher. He does not mention bishop but he does add in other writings deacon, elder and bishop, but none of these are said to have any authority over the other offices.
I generally agree that the terms bishop, priest and deacon (as well as "saint" the way St. Paul uses it) are all in flux in the New Testament writings, as so is the hierarchy of the Church. I don't know how exactly St. Paul received his consecration but my guess is that it happened on the road to Damascus directly from Christ.
But these are historical detail. The important thing to our understanding is that according to the scripture the Holy Ghost was sent to the Church first and that Church has a hierarcical structure, which Peter designed under the guidance of the Holy Ghost to perpetuate herself. The notion that men should arrive at their understanding of the scripture privately is nowhere to be seen in the New Testament, and is in fact warned against.