No. Oppo F7 does not have the front camera flash but it does have the display screen flash.
No. Oppo F7 does not have the removable battery.
Yes, Oppo F7 does have the OTG support. You also get the dedicated MicroSD Card slot.
Yes, Oppo F7 does have the FM radio.
The Oppo F7 is a good upgrade over the F5 in terms of battery life and SoC performance. The selfie camera is also easily one of the best in this phone's price range, and new additions like the Sense HDR mode and AI Beauty work well most of the time.