Some further detail provided by Nick Kristof's NYT column today, and his sort-of-a-blog on the NYT forums, here and here.
His column appears to clear up one of the remaining mysteries: namely, how did the doctors manage to put her in an ambulence and try to drive her to the American front lines (before getting turned back by firefights) two days before the rescue, if the hospital was crawling with Fedayeen until one day before the rescue?
Answer: the Fedayeen ordered that she be driven out in the ambulence.
And shot.
Lucky for her, the ambulence driver managed to persuade the hitman to spare her and desert, at which point they made their abortive attempt to drive her to the front lines. One of her fellow POWs was not as lucky; he was stuck, handcuffed and naked, in an ambulence the same day; his bullet-ridden body came back later that day and was buried on the hospital grounds.