Rape is condemned, and under Old Testament law could result in execution. As for slavery, virtually all societies held slaves. The Bible itself provides guidelines for the treatment of slaves, because slavery was so prolific at the time. In fact, parts of it also encourage emancipation of slaves. Anything can be used to justify anything, but it doesn't mean it actually supports it. As far as murder, let us note that there is a distinction drawn between murder and killing. Self-defense, for example, isn't considered murder.
Actually I believe the punishment for rape is that the rapist has to pay a dowry of 50 silver to the father and marry her while whoever got raped is forced to marry the rapist
Deuteronomy 22:28-29
If a man is caught in the act of raping a young woman who is not engaged, he must pay fifty pieces of silver to her father. Then he must marry the young woman because he violated her, and he will never be allowed to divorce her.
Pretty sure the punishment here is harsher on the person who got raped against their will than the actual rapist themselves, but this rule it seems only applies to women in your own tribe, raping and taking sex slaves is fair game.
Judges 21:10-24
So they sent twelve thousand warriors to Jabesh-gilead with orders to kill everyone there, including women and children. "This is what you are to do," they said. "Completely destroy all the males and every woman who is not a virgin." Among the residents of Jabesh-gilead they found four hundred young virgins who had never slept with a man, and they brought them to the camp at Shiloh in the land of Canaan.
The Israelite assembly sent a peace delegation to the little remnant of Benjamin who were living at the rock of Rimmon. Then the men of Benjamin returned to their homes, and the four hundred women of Jabesh-gilead who were spared were given to them as wives. But there were not enough women for all of them. The people felt sorry for Benjamin because the LORD had left this gap in the tribes of Israel. So the Israelite leaders asked, "How can we find wives for the few who remain, since all the women of the tribe of Benjamin are dead? There must be heirs for the survivors so that an entire tribe of Israel will not be lost forever. But we cannot give them our own daughters in marriage because we have sworn with a solemn oath that anyone who does this will fall under God's curse."
Then they thought of the annual festival of the LORD held in Shiloh, between Lebonah and Bethel, along the east side of the road that goes from Bethel to Shechem. They told the men of Benjamin who still needed wives, "Go and hide in the vineyards. When the women of Shiloh come out for their dances, rush out from the vineyards, and each of you can take one of them home to be your wife! And when their fathers and brothers come to us in protest, we will tell them, 'Please be understanding. Let them have your daughters, for we didn't find enough wives for them when we destroyed Jabesh-gilead. And you are not guilty of breaking the vow since you did not give your daughters in marriage to them.'" So the men of Benjamin did as they were told. They kidnapped the women who took part in the celebration and carried them off to the land of their own inheritance. Then they rebuilt their towns and lived in them. So the assembly of Israel departed by tribes and families, and they returned to their own homes.
Yeah the tribe of Benjamin, not enough sex slaves to go around so they had to kidnap drunk girls from some festival, not sure the tribe of Benjamin is who I should be feeling sympathy for.
As for guidelines for treating slaves what are we talking about here? The passage that says if you hit your slave so hard they die within 2 days you get a slap on the wrists but if they don't die you can hit them as hard as you like because they are your property? I know there are passages that say if you buy a Hebrew slave they can only serve for 7 years before being set free (again only if they are hebrew and only if they are male, but then again there is also a condition that allows them to be bound to eternal servitude as well) but it still does not change the fact that the Bible still condones, accepts and even encourages slavery which is a totally abominable practice that no ideology that claims a moral righteousness should preach.
As for murder you can try to call it self defense but I am not sure how killing those who work on the Sabbath constitutes as self defense, I don't see how killing those who worship false idols is self defense, I don't see how slaughtering a town and keeping the virgin women as slaves because they did not submit peacefully to the terms that they are either to submit to slavery or die is self defense.