No, she didn't know a lot of that. But she had faith anyways.
The angel Gabriel tells her all this shocking stuff, about having a baby that's God's son, and she's troubled at first, but at the end, she's just says: "I am the Lord's servant. May your word to me be fulfilled."
She didn't say "No" or "I'll think about it, come back in a few weeks." She had faith that this was God's oh-so-perfect plan for her and was just like, "Let's go, God!"
Mary was not much older than me, perhaps even my age, and I ask myself: Could I have faith like hers? Could I trust like she did? Would I be able to, without missing a beat, say "Yes"?
Her faith amazes and inspires me.
So, everyday, I will strive to have faith like Mary's.
"But the angel said to her, 'Do not be afraid, Mary; you have found favour with God. You will conceive and give birth to a son, and you are to call him Jesus. He will be great and will be called the Son of the Most High. The Lord God will give him the throne of his father David, and he will reign over Jacob's descendants forever; his kingdom will never end.'
'I am the Lord's servant,' Mary answered. 'May your word to me be fulfilled.' Then the angel left her." - Luke 1:30-33, 38