the discussion concerned Mary's need to offer a sacrifice for atonement....the fact that she may or may not have offered a sacrifice does not mean that she had need to do so. Sacrifices and other symbolic activities were, in those days, somewhat only symbolic. While most people were certainly in need of atonement, Mary was not.
Yes, she did. EVERYONE is a sinner because we all have a human father and inherited the sin nature. We sin because we're sinners and Mary is no exception.
Romans 3:9-26 9 What then? Are we Jews any better off? No, not at all. For we have already charged that all, both Jews and Greeks, are under sin, 10 as it is written:
“None is righteous, no, not one; 11 no one understands; no one seeks for God. 12 All have turned aside; together they have become worthless; no one does good, not even one.” 13 “Their throat is an open grave; they use their tongues to deceive.” “The venom of asps is under their lips.” 14 “Their mouth is full of curses and bitterness.” 15 “Their feet are swift to shed blood; 16 in their paths are ruin and misery, 17 and the way of peace they have not known.” 18 “There is no fear of God before their eyes.”
19 Now we know that whatever the law says it speaks to those who are under the law, so that every mouth may be stopped, and the whole world may be held accountable to God. 20 For by works of the law no human being will be justified in his sight, since through the law comes knowledge of sin.
21 But now the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it— 22 the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction: 23 for all have sinned and fall short of the glory of God, 24 and are justified by his grace as a gift, through the redemption that is in Christ Jesus, 25 whom God put forward as a propitiation by his blood, to be received by faith. This was to show God's righteousness, because in his divine forbearance he had passed over former sins. 26 It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus.