Yes. In fact, iTel S41 has ring indicator which blinks when you get a new notification.
Yes, iTel S41 does have a memory card slot.
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.
No. iTel S41 does not have a hybrid sim slot. It has 1 dedicated slot for MicroSD card and 2 dedicated sim card slots.
iTel S41 weight is just 155 Grams.