About the issue where your game is showing as having deleted DLC's or lost game totally. Go to your Steam app. Go to Steam < Settings < Downloads < Clear Download Cache. This should restart Steam and you should have access to your game & DLCs.
Who was the first person in the Realm of the Entity?
The way the Entity works is that it can bring a person form anytime period. A person from 2010 could be in the Realm of the Entity can be there longer than someone from 1947. So going off of that, who was the first survivor/killer that the Entity took?