We know this asking Mary to pray for us was something which the early Christians did as there are pictures in the catacombs of Mary, her arms raised in intercession. Surely after Jesus had left them, the Apostles loved and admired Mary who so generously gave Her Son to them. That's all veneration is... loving and admiring. It's not 'worshipping'.

Catholics feel that Mary was a special person by the nature of what God asked her to do and that she consented to do i.e. bear His Son. Thus her salvation happened before she was born i.e. she was saved in the act of falling into original sin. Being born without original sin (or the tendency to want to disobey God), although she was not perfect, sin did not hold the attraction for her which it holds for the average person. This attribute of Mary is called "The Immaculate conception" and is suggested in the Biblical passage in Luke which says that the angel who greeted Mary (i.e. Gabriel) greeted her as 'full of grace'. Although we all have grace in us, none of us would be 'full of grace'. Also notable is the way the angel greeted her... and keep in mind this was before she had done anything for the Lord... the angel greeted her as if she was his superior. Man, the Bible says is SLIGHTLY LOWER THAN THE ANGELS and in all other Biblical passages, angels greet men as inferior rather than superior. This one exception probably caused the people to call Mary the 'Queen of Angels'.