It appears the A5 screen size for an EFB by CASA is a "recommendation".
Probably just means that OzRunways just need to clarify qualify what is required to meet the requirements to use their software and an iPad instead of papter maps.
"battery boosters" are additional batteries that plug into your device to extend the power charge. They are cheap insurance against flat batteries in flight and I always carry a couple of fully charged one in my nav bag.