Here's a thought on elders: they are men appointed to lead the body. I was reading Titus and a commentary on this topic, and found this: "Appoint elders in every city as I directed you" (Titus 1:5b). By doing this, Paul is going against customary cultural practices because both the Jewish synagogue and Greco-Roman society commonly practiced one-man oversight. Thus Paul's choice of the elder structure of government is intentional. He is not simply accommodating himself to current social norms. His instruction to Titus establishes an apostolic directive that should be followed by Christians today.
Moreover, the appointment process seems to be the installation of a leadership model, and not just asking mature believers to lead.