Moto C has a decent pair of the camera on both the sides. The rear camera has 5.0 MP resolution camera with Autofocus and LED Flash. There are many other options available like beautifying software, HDR, Burst mode,etc. The front camera has 2.0MP and HDR support. The front camera also has LED flash and you can also use display screen as flash.
No. Moto C is not a water resistant phone.
Yes, you will get a pair of headphones with this mobile phone in the box.
Yes, you can use.