**drum roll**
I wrote a download-all button today! Will be in next release which will be AWESOME (we've just spent all week day & night coding to add a bunch of new cool stuff).
PNG maps: I don't have any that are not copyright Commonwealth Australia.
NZ maps: AirwaysNZ aren't playing the game yet. Still bugging them.
Expect a major update in a few weeks hopefully. More work/testing needs to be done on our new stuff before release.