I have two questions:
1) Is there anything i need to do after the final challenge with Orgram? The quest book doesn't give any clue, I don't see the typical "The rest of this event is still WIP" either, so I guess there is more I need to do to progress the Orc's War quest
2) I found the thief's key in the mountains' tunnels, where is his hideout?
1) After finishing the challenges you need to go back to your hut and rest until morning to trigger the Nameless questline, though this questline will only trigger if you've already finished Lizards tresuare and if you've done the good ending of it
2) We have no idea as of now because the place doesn't technically exist yet¯\_(ツ)_/¯