Revives are not allowed during the darkness areas in the raid. Wiping is sometimes better if things either go wrong, or if a player dies etc. Dying and starting from the check point gives a fresh start of the encounters are glitchy or not going well. Upon the weekly refresh you can run normal mode then hard mode and receive rewards per character. If you start with hard mode you will only be able to per character as hard mode counts as hard and normal mode loot so normal will not reward you if you try playing it right after. So normal then hard or just hard mode once per character. Hope that helped, if you have any other questions feel free to ask!