For God it is. How can it not be? God created everything, including Mary to be the mother of Jesus. She had only the illusion of free will.
No, Catholics reject the heresy of Calvin's TULIP. Everyone, including Mary, has/had full freewill. Mary freely chose to become the Theotokos.
You are undermining the Protestant position on Mary's sinlessness. If she had no freewill, she was no more capable of sin than the beasts of the field. Either way, Protestantism is undermined.
Peace be with you