The "priesthood" (as in ordained priesthood) in those days consisted of elders (bishops) and heir deacons (disciples). Priest are introduced towards the end of the first century (which is why Paul doesn't mention it; and that historical fact should be an eye-opener for you) because the Church became too wide-spread for one bishop and needed deputies. Priests act only under the authority of an apostolic successor, a bishop.
You'll agree, Kosta, that presbyter, as a separate office from a bishop , emerged only after several decades, but that when Paul uses the term, "presbyter," he is using the term to describe the role of a priest, (that is, one who PRESides over a mass) even if that role is performed by one who is also a bishop, right?