No. Nokia 5.1 does not have the front camera LED flash but it does have the display screen flash.
Yes, Nokia 5.1 is a VoLTE mobile phone.
No. Nokia 5.1 lacks water-resistance.
No. Nokia 5.1 has 2 dedicated slots for the sim cards and 1 dedicated slot for the MicroSD card. You can use up to a 128GB memory card in Nokia 5.1.