There are two topics in your post. I'll address the one consistent with the title first.Acts 20:28refers to the elders of the church of Ephesus 'bishops.' It tells the elders to pastor the church of God over whom the Holy Ghost has made you overseers.I Peter 5 tells the elders to pastor the flock of God, taking the oversight (compare to Greek for bishop) thereof. Titus 1uses 'elders' and 'bishop' to refer to the same ministry. Elders are told to pastor the flock of God. Peter gives a few instructions in I Peter 1. Paul writes that the bishop is to be 'apt to teach.' In I Timothy 5, he writes of elders who rule well being worthy of double honor, especially those who minister in preaching and teaching.Elders just suddenly show up on the scene in the church in Acts 9without explanation, but actually they continue over from the Old Testament. There were elders among the people of Israel. Moses called together 70 elders on one occasion and the Lord put the spirit that was upon Moses upon them and they prophesied. Two that were in the camp also prophesied. Israel had elders in their tribes in the desert. Later, when the tribes settled in the promised land, there were elders in the cities. In New Testament times, there were elders in these cities that were involved in the synagogues, and the national Sanhedrin were considered the heirs of the 70 elders. A portion of these elders were specifically referred to as 'elders', who had apparently been raised up from among judges among the people. Chief priests and scribes made up the other part of the Sanhedrin.Sources about first century Jewish elders, judges, and the Sanhedrin tend to refer back to Tractate Sanhedrin, something I had never been able to find (until just now as I was writing this), but I read a portion that describes the requirements for judges, who could potentially become Sanhedrin elders. Requirements were more elaborate, but somewhat resembled Paul's requirements for bishops in some ways. We need to keep in mind that the author Maimoinedes lived a thousand or so years after the fact, too.Something to keep in mind is that the Old Testament elder role is a male role. It doesn't make sense that they would have called their women 'bearded ones.' The members of the Sanhedrin were apparently also male. If we want to consider historical context and similarity between the requirements for bishops/elders and Jewish requirements for judges who could become members of the Sanhedrin, that Jewish judges had to be married men with children (so that they might know mercy.) If we are looking at a cultural and historical approach, that is something to consider. Something else to consider is that the Old Testament, and to some extent the New Testament, is patriarchal. The tribes of Israel, which had elders, first as tribes, then as tribally arranged cities, were large families. Elders would have been prominent men in larger extended families. New Testament churches in the first century were large spiritual extended families. The New Testament tells wives to submit to their husbands, and speaks of women not teaching men and/or their husbands or usurping authority over them. Putting women 'in charge' of their husbands in church roles would be contrary to this principle. Notice that these teachings about women not teaching men/husbands appear just before the qualifications for bishop in I Timothy. The bishop must also be 'apt to teach.' When it comes to deacons, the text may actually allow for women deacons. The KJV says, 'Even so must their wives' which could also be translated, 'Even so must their women'. That could be allowing for female deacons, so we have requirements for deacons, who are to be the husband of one wife, and of 'their women' who have certain requirements as well