God�s commands

1-how does this quotes of yours justify in anyway the orders given to the prophets of OT by God toward indescriminate and unjust killings of the innocent babies, children, animals and destruction of crops and property.

Because that is what the pagans did to Gods own people from Abraham onwards, so in return God did it to them!  It is called; �they will reap what they sow� which is justice.

Why did Jehovah decree the extermination of the Canaanites?

The historical account shows that the populations of the Canaanite cities conquered by the Israelites were subjected to complete destruction. (Nu 21:1-3, 34, 35; Jos 6:20, 21; 8:21-27; 10:26-40; 11:10-14) This fact has been used by some critics as a means for depicting the Hebrew Scriptures, or �Old Testament,� as imbued with a spirit of cruelty and wanton slaughter. The issue involved, however, is clearly that of whether God�s sovereignty over the earth and its inhabitants is acknowledged or not. He had deeded over the right of tenure of the land of Canaan to the �seed of Abraham,� doing so by an oath-bound covenant. (Ge 12:5-7; 15:17-21; compare De 32:8; Ac 17:26.) But more than a mere eviction or dispossessing of the existing tenants of that land was purposed by God. His right to act as �Judge of all the earth� (Ge 18:25) and to decree the sentence of capital punishment upon those found meriting it, as well as his right to implement and enforce the execution of such decree, was also involved.

The justness of God�s prophetic curse on Canaan found full confirmation in the conditions that had developed in Canaan by the time of the Israelite conquest. Jehovah had allowed 400 years from Abraham�s time for the �error of the Amorites to come to completion.� (Ge 15:16) The fact that Esau�s Hittite wives were �a source of bitterness of spirit to Isaac and Rebekah� to the extent that Rebekah had �come to abhor her life because of them� is certainly an indication of the badness already manifest among the Canaanites. (Ge 26:34, 35; 27:46) During the centuries that followed, the land of Canaan became saturated with detestable practices of idolatry, immorality, and bloodshed. The Canaanite religion was extraordinarily base and degraded, their �sacred poles� evidently being phallic symbols, and many of the rites at their �high places� involving gross sexual excesses and depravity. (Ex 23:24; 34:12, 13; Nu 33:52; De 7:5) Incest, sodomy, and bestiality were part of �the way of the land of Canaan� that made the land unclean and for which error it was due to �vomit its inhabitants out.� (Le 18:2-25) Magic, spellbinding, spiritism, and sacrifice of their children by fire were also among the Canaanites� detestable practices.�De 18:9-12.

2-Not even a man, loving and just ruler will do this to his enemy.  It seems like that there are many mortals in this world that are more just and loving than the God of the Bible, those who would at least spare more if not less than babies, children, livestock, fields and cities from utter destruction?

God will give like for like, that is true justice.

He gave like for like to all the enemies of his people, Isreal in protecting them!

I know and understand that God directly does take life, destroys property and life as He is the giver of life and all. But through His prophets He never taught them unjust and unkind behavior, as they were to teach God's Justice and Compassion, at all times, for that they were sent.

Nowhere in any other "Holy book" have I found order and promotion of such behavior as in the Bible. Here is another one of those commands claimed to be coming from God. 

THE QURAN  SAYS:-

Sura 5.033

YUSUFALI: The punishment of those who wage war against Allah and His Messenger, and strive with might and main for mischief through the land is: execution, or crucifixion, or the cutting off of hands and feet from opposite sides, or exile from the land: that is their disgrace in this world, and a heavy punishment is theirs in the Hereafter;

PICKTHAL: The only reward of those who make war upon Allah and His messenger and strive after corruption in the land will be that they will be killed or crucified, or have their hands and feet on alternate sides cut off, or will be expelled out of the land. Such will be their degradation in the world, and in the Hereafter theirs will be an awful doom;

SHAKIR: The punishment of those who wage war against Allah and His messenger and strive to make mischief in the land is only this, that they should be murdered or crucified or their hands and their feet should be cut off on opposite sides or they should be imprisoned; this shall be as a disgrace for them in this world, and in the hereafter they shall have a grievous chastisement,

Sura 22.009

YUSUFALI: (Disdainfully) bending his side, in order to lead (men) astray from the Path of Allah: for him there is disgrace in this life, and on the Day of Judgment We shall make him taste the Penalty of burning (Fire).

PICKTHAL: Turning away in pride to beguile (men) from the way of Allah. For him in this world is ignominy, and on the Day of Resurrection We make him taste the doom of burning.

SHAKIR: Turning away haughtily that he may lead (others) astray from the way of Allah; for him is disgrace in this world, and on the day of resurrection We will make him taste the punishment of burning:

Sura 8:12  I shall cast terror into the hearts of the infidels. Strike off their heads, maim them in every limb.

Sura 9:29

�Fight those who believe not in Allah nor the Last Day, nor hold that forbidden which hath been forbidden by Allah and His Apostle, nor acknowledge the Religion of Truth, (even if they are) of the People of the Book*, until they pay the Jizya** with willing submission, and feel themselves subdued.�

*Christians

**The Head Tax levied on non Muslims living in an Islamic country.

PARADISE FOR SOLIDERS!
The Holy Qur'an by Abdullah Yusuf Ali p.1315 says at:-
Surah (Chapter) 47:4
"4   Therefore, when ye meet* the Unbelievers (in fight), smite at their necks; at length, when ye have thoroughly subdued them, bind a bond firmly (on them): Thereafter (is the time for) either generosity or ransom: Until the war lays down its burdens. Thus (are ye commanded): But if it had been Allah's Will, He could certainly have exacted retribution from them (Himself); but (He lets you fight) in order to test you, some with others. But those who are slain in the way of Allah,-He will never let their deeds be lost.
  6   And admit them to The Garden** which He Has announced for them."

*Footnote No. 4820 on page 1315:-
"When once the fight (Jihad) is entered upon, carry it out with utmost vigour, and strike home your blows at the most vital points (smite at their necks) both literally and figuratively. You cannot wage war with kid gloves."
**Footnote No. 4826 on page 1316:-
"The Garden which He has announced for them: the state of Bliss which is declared in Revelation to be destined for those who serve Allah,"
Surah 4:101 Section 15. When ye travel through the earth, there is no blame on you if ye shorten your prayers, for fear the Unbelievers may attack you: For the Unbelievers are unto you open enemies.

1Samuel 15:1......Do not spare them; put to death men and women, children and infants, cattle and sheep, camels and donkeys.' "

Who were these Amalekites that went striking down those exhausted and weary ones? Who were these people that did not fear God? Amalek was a grandson of Esau. No wonder! Esau was the one who sold his birthright to his brother Jacob. So the offspring of Amalek were determined to perpetuate the hatred Esau had for his brother Jacob, even more than three centuries later. So they launched this unprovoked attack on the offspring of Jacob. Because of this dastardly action Jehovah God decreed that they should be wiped out, which meant ultimate extinction of the Amalekites.

During the period of the judges of the nation of Israel the Amalekites continued to be adversaries of Israel and they shared with other nations in assaulting Israel. (Judg. 3:12, 13; 6:1-3, 33; 7:12; 10:12) About four centuries after the Israelites left Egypt, Samuel the prophet of God said to King Saul: �This is what Jehovah of armies has said, �I must call to account what Amalek did to Israel when he set himself against him in the way while he was coming up out of Egypt. Now go, and you must strike down Amalek and devote him to destruction with all that he has, and you must not have compassion upon him, and you must put them to death, man as well as woman, child as well as suckling, bull as well as sheep, camel as well as ass.�� (1 Sam. 15:2, 3) Jehovah did not forget!