People praying the rosary, singing Mary songs, etc is a form a worship no matter how much catholics want to deny it. These things only belong to God. I have seen pictures of Mary sitting next to God in His throne as she was was co-equal with God when she was only a human like any of us. Of course she was blessed by God and deserves to be honored but it does not imply a godly position. God chose her by His grace, grace is God giving us something we dont deserve.
Why do we need Mary as mediator when Jesus Christ already paid the price for our sins so that we could approach God directly? Saying that we need Mary as mediator is like saying that what Christ did in the cross is worthless or meaningless. Read Luke 23:45 which says that the curtain in the temple was broken apart in two, this symbolizing that the use of mediators (like in the old testament where only the priests could enter the most holy of the holy places and approach God to intercede for people) was terminated.