You're doing a fine job so far! The one thing I could find that you need to look at as far as Part I is concerned is about the "pop up" hole in the basement. I looked into it and that building is owned by Alefantis, but it's the showroom/workshop of a guy named Joseph Margot (Margotworks) The photo of the two guys looking into the hole is of him and someone else. I don't know what his ties to Alefantis are if any but here's his website and if you scroll through his pics you'll see the one in question. You're right about the infamous "killroom" being somewhere else. I don't know about Pegasus Museum which is supposed to be at the same address.
http://www.margotwork.com/#/process/