And yet none of that is taking place today...because these citations of yours are not prescriptive to all people at all times, but are limited to those who were hearing or reading at the time of their writing. They are culturally bound.
"St Paul's advice in 1 Timothy 2:12, in which the saint says: "I do not permit a woman to teach or to have authority over a man, she must be silent."
The comment Paul makes is perfectly consistent with the culture of the day and is prescriptive for the purpose of keeping peace in the local assembly. The actions of the women in question were disruptive and preventing the larger message from getting across. The problem was erupting within the Church at Corinth.
"Maybe endorsing genocide...1 Samuel 15:3: "This is what the Lord Almighty says ... 'Now go and strike Amalek and devote to destruction all that they have. Do not spare them, but kill both man and woman, child and infant, ox and sheep, camel and donkey.' "
Yep. The Lord said this and expected it to be done. He didn't tell "you" or "I" to do it though. It was a command to the Hebrews at that time on how to deal with their enemies. It also was consistent with the culture and wouldn't have been a shock to the ones receiving it. It was also a 100% effective way of making sure that a future generation wouldn't rise up and go to war with you. Those within the community that weren't guilty of the horrid things this society was doing, i.e. child sacrifice, would find themselves in a better state than had they been allowed to live. The approach is pragmatic to the core, eliminating a present problem, and any possibility of a future one. The Hebrews actually failed to do this on a couple occasions and were at war with the future generations for centuries. So, while we would never do this, it was consistent for its time.
"This delightful Psalm 137, which celebrates this terrible revenge: "Happy is he who repays you for what you have done to us / He who seizes your infants and dashes them against the rocks."
This us just a women lamenting what was done to her people, wishing justice on those who massacred them. How about reading the whole passage here. Babylonians had committed atrocities against the Jews during their captivity. This is just a women lamenting that fact and saying that the Jews would rejoice over the same being done to their enemies' children. There is no prescriptive act here, just mourning of someone who was entirely human.