In regards to the Parking Brake query, take a look at the Emergency Evacuation checklist. The first item is Parking Brake On - There can only be 2 settings (On/Off) as per the pedestal in which we set the Park Brake. Airbus FCOM only stipulate Park Brake - Set after initial push back! I believe Airbus rely that as professionals we can distinguish the reasons why and not be spoon fed everything.