The dead ghost in the room where you kill the gate lord on Venus can be picked up infinitely. Everytime you go there you can pick it back up and adds another dead ghost to your "dead ghosts picked up" count. I have all 68 dead ghosts but my count says I have 70. I definitely remember picking up this dead ghost twice more after showing its locations to some of my friends. Also, don't forget about my thread (made long before this one): https://www.bungie.net/en/Forum/Post/86782620/0/0 I can confirm most of the issues you mentioned in your post.