Oppo F9 has ARM-Mali G72 MP3 GPU. The peak frequency of the GPU is 800 MHz.
Yes, Oppo F9 does have the dual rear camera set up. The main camera has 16MP resolution while the second rear camera has a 2MP resolution.
No. Oppo F9 has MicroUSB port.
No. Oppo F9 does not have the front camera flash but it does have the display screen flash for the front camera.
The most striking feature of the Oppo F9 is the big display with the waterdrop notch. It is well designed, delivers good battery life, and offers decent performance for the price.