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. In fact, iTel S41 has ring indicator which blinks when you get a new notification.
Yes, iTel S41 runs on the latest Android 7.0 and thus having support for the multi windows operations.
Yes, iTel S41 does have the LED flash with the front camera.
Yes, iTel S41 does have the eye protection mode which reduces strain for long reading.