Long, but whatever.
First off, the Quran does not state anything of that which you have listed to be done, meaning that it never said to have slaves, alot of wives, or to marry young women.
Muhammad (peace be upon him) was the defender of the orphans and even the newborn children. He ordered the care of orphans and feeding of the poor as the means to enter Paradise and if anyone held back the rights of those who were destitute, they could forget about ever seeing Paradise. He also forbade the killing of new born girls, as was a custom of ignorance according to primitive Arab traditions. This is referred to in the Quran; when, on the Day of Judgment those who practiced the evil deed of terminating the life of their own infant daughters, will have it exposed, the Quran says:
"And when the female (infant) buried alive (as the pagan Arabs used to do) is going to be asked; about what sin could she (as an infant) have possibly committed."
[Noble Quran 81:8]
Those who spend their wealth (in Allah's Cause) by night and day, in secret and in public, they shall have their reward with their Lord. On them shall be no fear, nor shall they grieve.
[Noble Quran 2:274]
Muhammad (peace be upon him) ordered men not to "inherit women against their will," and not to marry them accept by mutual consent and never to touch their wealth or inheritance in order to improve their own financial conditions.
O you who believe! You are forbidden to inherit women against their will, and you should not treat them with harshness, that you may take away part of the Mahr you have given them, unless they commit open illegal sexual intercourse. And live with them honorably. If you dislike them, it may be that you dislike a thing and Allah brings through it a great deal of good.
[Noble Quran 4:19]
We also notice from this verse, He forbid the common practice of wife-beating and abuse, (his own wife said he never once hit her).
He never once engaged in sex outside of marriage, nor did he ever approve of it, even though it was very common at the time. His only relationships with women were in legitimate, contractual marriages with proper witnesses according to law. His relationship to Ayesha was only that of marriage. He did not marry her the first time her father offered her hand to him in marriage. He married her only after she reached the age of puberty and could decide for herself. Their relationship is described in every detail by Ayesha herself in the most loving and respectful manner as a match truly made in heaven. Ayesha is considered as one of the highest scholars of Islam and lived out her entire life only having been married to Muhammad (peace be upon him). She never desired any other man, nor did she ever utter a single negative statement against Muhammad (peace be upon him).
Muhammad (peace be upon him) ordered men to "provide and protect" women, whether it was their own mother, sister, wife or daughter or even those of others, whether they were Muslims or not.
"Men are the protectors and maintainers of women, because Allah has made one of them to excel the other, and because they spend (to support the women) from their means. Therefore the righteous women are devoutly obedient (to Allah and to their husbands), and guard in the husband's absence what Allah orders them to guard (e.g. their chastity, their husband's property, etc.).
As to those women on whose part you see ill conduct, admonish them, refuse to share their beds, startle them (set forth a clear example or parable for them, to make clear the point of what is going on before divorcing them) so if they return to proper obedience (to Allah and their husbands), do not annoy them any further. Surely, Allah is Ever Most High, Most Great."
So now I ask you, does the Quran allow slaves? Did the prophet peace be upon him take slaves?