No. Samsung Galaxy J7 Max is not a waterproof mobile phone.
Well, Samsung has recently announced that they will try to provide as many updates possible. But they have not said anything specific with respect to Android 8.0 but we hope that this model should get the update in future.
Samsung Galaxy J7 Max is a dual sim mobile phone.
No. You cannot use CDMA sim card in this phone.
Yes, It's a VoLTE mobile phone.
Samsung Galaxy J7 Max is worth considering if updated software and a great camera are your priorities.