Their current allotment is the largest tonnage anyone is allowed plus 10 battleships and 10 battlecruisers on top of that which if we assume an average weight of 30000 tons is an extra 600000 tons aka twice the next highest allotment.
Feels a little like a mass death scenario but as far as my two cents go.
Radioactive and chemical could kill a lot of people but they're rather limited and noticeable.
A biological weapon that was quietly released and had a decent incubation period before symptoms if released near an airport...
I don't know if it is as simple as being a bit more aggressive, if they had all landed on their correct landing zones in Anzac cove it would have helped a bit but honestly to secure that landing they had to climb a cliff face that had machine gun nests with overlapping fields of fire.
Perhaps...
Even with Nash in charge it's likely that there would still be budgetary issues due to the draw down from WW2.
However without Holland it's possible PAYE would never have been implemented.
Holland also created the Tourist Hotel Corporation so maybe NZ would be more focused on the primary...
There is a good chance Richard Pearse could have stepped in, he is one of the people claimed to have flown before the Wright brothers although there is a good deal of evidence to dispute that he was certainly flying in and around 1904.
He was however a paranoid recluse who lived in the arse...