No. Exactly we cannot say that Nokia 8110 4G is a waterproof device. But it is IP52 certified. Means it is splash proof. You are protected up to some extent by water.
Yes, Nokia 8110 is made of Polycarbonate material, which does not allow power transmission and thus it makes a shockproof mobile phone.
Yes, Nokia 8110 4G does have the FM radio.
Yes, Nokia 8810 4G does have the VoLTE support. You can make calls via VoLTE enabled network easily.