If two power cords, figure out which one powers the battery charger. Mine is now marked on the boat and on the cord.
With boat plugged and powered in it is fine to leave batteries on while unattended.
The 'fridge is happy running off of battery power (topped by charger) or off of shore power.
The empty accessories breaker position permits future expansion for adding additional stuff. A good rule of thumb is to stop adding stuff, prior to the boat sinking because of all that added mass.
