OPPO A37 has 5-Inch HD IPS display which works with 1280 x 720 Pixels resolution and produces 294 PPI. The display supports up to 16 million colors and the aspect ratio is 16:9 with 68.05% display area. The phone do not look big in your hand and you can use it with just one hand, even the size is 5-inch. It has Corning Gorilla Glass 4 protection against scratches.
Yes, you can use 64-bit apps on OPPO A37.
Yes, OPPO A37f does have OTG support.
No. Oppo A37 is not a waterproof mobile.
Once again Oppo has presented us with a device that is functional, to the point and performs just as expected.