I agree about the horn "remembering" being weird. It does fit well with "To die and live again, and live once more a part of what was!" - he relived that half-hour or so a second time.

There's also mention of it when Elayne gives her speech.

I've always thought there was a problem with this explanation. Is he saying that Ingtar showed up to release Fain with a Fade, and Fain took the time to torture the Fade before leaving? He has to find out about Toman Head before leaving because he leaves the message in the cell.