Re Recircs - we have told you a few times - ask Boeing. We do not know the exact flow requirements.
Re Pack controls: You need to forget left and right pack control in the 3/500 sense for the 4/800. Think of these ELECTRONIC controllers as mysterious black boxes that get info from both packs and all three zones. They will set the pack delivery to satisfy the zone with the most cooling need. Obviously if that is the cockpit they will adjust the left pack (Right Controller): if the aft zone, they may well control just the right pack (Left Controller) or both (Left and Right) etc etc
STANDBY is a mode which takes over the other controller task when it fails. Left and right are effectively meaningless in this context and should be forgotten. This should all be in your 'CBT' - which one are you using?