Yes, Vivo V5s 64GB comes with front camera LED flash.
Vivo V5s comes with latest Android 6.0 Marshmallow OS which has got Vivo's patented FunTouch 3.0 skin layer. Since the device is newly launched, we do not expect that company will release the new software update immediately.
Yes, you can use 2 4g sim cards in this phone.
Vivo V5s has dual core GPU.