Of course the Theotokos was in need of a Savior just as we are. If anyone has stated the opposite, they certainly do not understand Orthodox (or Catholic) doctrine. Had she not been subject to the effects of the ancestral sin, she would never even have died.
With regard to Calvin, yes, he did apparently believe in the perpetual virginity of Mary. As I recall, for him it was a simple as recognizing that she had been known as "the Virgin Mary" from the earliest times.
He rightly commented (again, as I recall) that had she not been ever-virgin, no-one would have given her the title of "the Virgin." To have been a virgin at some point in one's life is a universal phenomenon -- even conceiving in virginity would not be a reason to continue to refer to her as "the Virgin Mary" after her death.
I understand Mary was not excused from the penalties of Adam such as sorrow and death; but I believe the Church's position on Mary was that she was "free" from original sin which is a major point of the Immaculate Conception. In other words, she lived a perfect life. That would mean that if anyone lived a perfect life, following all laws and commandments of God, then it wouldn't matter. They would still need a Savior because of Adam. Is this correct?