I hesistate to try and explain things which I myself am not prepared to do so adequately. While I believe the things I see on Television are not images of my imagination but have a scientific reason to how the TV functions to display images that I do not yet understand, I accept it on faith one might say that the TV works within the bounds of reality and reason without my full understanding of how. As for the Queen of Heaven title, that is one of the things that I currently accept on faith without currently possessing the level of full understanding of how/why until I actually do understand. If I may, I will offer an explanation which may be met with plenty of disagreement by many.
Mary is the mother of God, Jesus being the incarnation of the Divine Word in the flesh (Jesus is God : Mary is the mother of Jesus : Mary is the mother of God). Mary is the mother of God and she is the daughter of God the Father, as a creation of God. These two relationships make her the Mother of God through her role as Mother to Jesus the Son, and Daughter of God through her role as a creation of the Father. Now, as it is said in scripture that she concieved of the Holy Spirit, the Church proclaims that she is in a way Espoused to the Holy Spirit. So, she has the unique relationship to the Trinity that no other human has ever had: She is the Mother of God, a Child of God (Daughter), and is Espoused of God. Naturally, God is the King of Heaven (Jesus is King of King and Lord of Lords).
Now, as God is King of Heaven, Mary's relationship to the Trinity is what makes her Queen of Heaven. All kings in history have had mothers, and their mothers have been queens even while their children were in power. An example being the Queen Mother of England despite there being the ruling king or queen. If Mary is in a special way espoused to the Holy Spirit who is God and is in fact King of Heaven, then for this reason Mary could have the title Queen of Heaven. In the Hebrew tradition, I have heard, the mother of the king was considered the queen. Mary is the mother of Jesus. Jesus is the King...kings are only ever born of queens...ergo...
Of course, in the ancient customs, the queen was not equal to the king, and the queen did not rule of her own athority as we are now accostomed to thinking of queens. The is important to note as the Queenship of Mary is not in any way equal to the Kingship of Christ. This is where a lot of misunderstanding can occur, that people might think that the Catholic belief in Mary's Queenship puts her with equality with God, when in fact it certainly does not.
Also, the wikipedia link which was provided has this as an explanation:
"In the New Testament, the title has several biblical sources. Mary is mother of the messianic king. Luke 1:32 says of Jesus, He will be great, and will be called the Son of the Most High; and the Lord God will give to him the throne of his father David. He will rule over the house of Jacob forever and his reign will be without end. It is therefore held in Christianity, that the throne of King David has passed to Jesus The biblical precedent of ancient Israel is that the mother of the king becomes the Queen Mother. Since Jesus is heavenly king, of the lineage of David and Solomon, many see Mary as Queen Mother."
As for everyone being God's Child, I can only day that the Devil created nothing on earth. Satan has not willed anything into existence as God did, because satan is merely a creature. God's role in creation makes him the Father of all creatures, and for this reason, all creatures are subject to him. Some of these creatures deny him (satan) and choose to follow their own wills or the wills of other creatures, denying the legacy which God wants for thim through sin. They are his children in the sense that he created them. Not all children inherit from their fathers, especially those children who choose to make themselves bastards by following satan.