I know that, in addition to the Church's martyrs, God-bearers, and so forth, the Holy Prophets count as saints. But: ( 1 ) Who else from the pre-Christian era might be ayioi?
"Ancestors, fathers, patriarchs..."
and what is the criteria?
Sanctity? I'm not sure I understand the question.
( 2 ) After the schism, how are Western "saints" evaluated for sanctity? or are they ever?
Officially, post-schism "saints" of non-Orthodox Churches are not evaluated one way or the other.
( 3 ) Are biblical or divine qualities ever ayioi? For example, I understand that there was a real-life St. Sofia with daughters Agapi and so forth. But is that coincidental to Holy Wisdom, i.e., is Wisdom sainted itself?
"Holy Wisdom" is Christ. We don't canonise qualities, virtues, "good stuff", etc.