These are appearently non-military related papers.
The upper and middle ones are for Post Office Fixed Term Deposit certification and it is possible these are post ww2 ones.
The third is a written instruction regarding shipping of goods from a company probably in Saipan. The nature of the goods were not stated.
On the last lines on the third document are the names of two vessels; Yokohama Maru and Amagi Maru. Both were NYK ships.
Yokohama Maru was sunk off Salamaua in New Guinea on March 10th 1942 and from this the document presumed to be issued sometime before the height of the war.
The reason I ask is that the A6M3 reportedly has a +300 mm Hg war emergency power setting, but contemporary photographs of an example tested by the US show a coloured sector ending at +250 mm Hg.
Of course, this difference would have an impact on the performance of the type.
This should answer a bunch of your questions on Japanese manifold gauges and how they work. First page is source. Its the best reference book I would recommend for knowing the inside workings of Japanese aircraft.