1. Fluid overload does not produce ARDS, but pulmonary edema, which should respond to diuretics. On the other hand, ARDS (from other causes) is worsened by hypervolemia; that's true. One could also argue that many liters of crystalloid are pro-inflammatory, but that number is much higher than 3.8. My guess is that this patient has a ton of postop inflammation at the surgical site. Best prevention? How about a much shorter procedure and less messing around with the lung?
2. You should have replaced some of the blood loss (once significant) with blood. Crystalloids (and even colloids) will leak into tissues, especially the dependent ones, including the lungs. I would have kept the fluids to less than 1.5-2L. But then you would have been accused of causing TRALI or TACO. When the surgeon is incompetent, just blame it on anesthesia.
3. PPV induces ADH secretion, i.e. fluid retention. If the MAP is over 75, I wouldn't worry about low urine output or AKI. I would worry about poor peripheral perfusion due to too much pressor.
4. COPD, elderly, BMI 57, h/o delayed emergence, long surgery, big fluid shifts... WTH was wrong with your attending to even try to extubate her in the OR? She must have had as much sevo in her almost 100 kg of adipose tissue as the sevo reservoir on the anesthesia machine.