No. Oppo A5 does not have the front camera LED flash but it does have the display screen flash.
No. Oppo A5 is not a water-resistant phone.
No. Oppo A5 has MicroUSB 2.0 port.
Yes, Oppo A5 does have the dual rear camera. The primary rear camera is of 13MP while the secondary rear camera is of 2MP.