Yes, you can use 2 different WhatsApp accounts in iTel S41. Not only that, you can use 2 different Facebook, Instagram and Twitter accounts as well.
Yes, iTel S41 does have the LED flash with the front camera.
Yes, iTel S41 does have VoLTE support.
Yes, It does have.
No. iTel S41 does not have a hybrid sim slot. It has 1 dedicated slot for MicroSD card and 2 dedicated sim card slots.