1) You have to destroy the totem in the first room on the left in the mines. This should free the sceleton minors who give you the password for the big door in the very east of the mines. You have to sneak past the death knights. If you're already past the spot where you met Leandra you have to flee behind her. There is a portal north-west of her position which transports you to the old temple where you can find the spell for the blood.
2) That's how it should be. Just split your group and go through the poisoned area one by one. If one char is through toggle to his inventory and send the amulet to the next char and so on. Tedious, but working.
3) You should have found a "broken orc horn" or something like that at the end of the tomb where you found the corpse (just before the bloodstone. If you show that broken orc horn to the leader of the humans in Hunter's Edge the quest in the town will continue.
