1 Corinthians chapter three.
I am confident that Blessed Mary was born, but I do not recall a Catholic tradition about her birth specifically, do you mean the immaculate conception? That is about Blessed Mary's conception rather than her birth.
I quite like asking Blessed Mary to pray for me.
The saints are mentioned many times in the New Testament, they watch us (the great cloud of witnesses) they pray about and for us (saints under the altar in Revelation) and we ask them to pray for us (the prayers of a righteous man avail much.
I do not think any Pope added any doctrine to the bible.
Then, what does the "immaculate conception" mean? I learned that it was Mary's conception so that Jesus' conception could be pure. Nothing in the Bible indicates that to be the case.
You may like praying to Mary, but how can you be sure that she is listening as a human soul in heaven? She is not divine. Besides, Jesus taught us to pray to our heavenly Father in the Lord's Prayer, not to Mary or the saints.
Again, how can you be sure the human souls of the saints hear you and will pray for you. They aren't present everywhere, the way God is. You have no biblical basis for praying to Mary and to the saints at all, but there is a basis for praying to the Father through Jesus.
The "great cloud of witnesses" in Hebrews 12 are the Old Testament believers of the previous chapter. Do you pray to Abraham?
The Popes have added all of this plus purgatory and other beliefs to the Bible.