I neglected to respond to that. Yes, not only is sinlessness of Mary not contradicted by any verses you brought up, as I have shown, but also there is a positive statement indicating her sinlessness even prior to the Annunciation, and that is Luke 1:28. The original Greek has her described by the angel as "kecharitomene", word unique in the New testament, indicating fullness of grace in the past tense. Now, where grace abounds, sin cannot abide.
So, my "are highly favored" has the tense wrong? The actual words were equivalent to: "was filled with special grace, that no one else has ever had, from before birth"? That does seem like a pretty radical difference.
How is it that we as believers have grace, but yet the remnant of sin remains and we still sin? Grace only abounded in Mary? You are disagreeing then, that the word used here is the same as in Eph. 1:6 which describes all believers as being equivalently "filled with grace"?
Finally, if Mary was so filled with perfect grace that she was sinless her whole life, she had the most surprising reaction to being told that she would be the mother of Jesus. Why would she need to be told? Why would she have been afraid? Also, wouldn't someone filled with grace from before birth know who she was? She even asked questions. For someone who was sinless, she sure didn't seem to understand that she was different from any other human who had ever yet lived.