don't see the point in keeping them at the top - it doesn't make you answer them more.
i would think most people go back through the questions until they see one they recognise, which means thats as far as the new questions go, so mixing them up can make this confusing.
i didn't look at a few topics for ages before i realised that the questions had been frozen, because whenever i clicked on the topic i would come to a familiar question and think there had been no new ones since.