I found the site, here are some first observations
12 32 35 21 24 from 0001.txt gives you a five-number sequence which could be related to your 5 x 5 grid puzzle
Paul's address 80 E. 11th Street in NYC is a real address of a building called the St. Denis. Furthermore, on the outside of that building is R O L A N D ... one huge letter in each of six windows. Probably not a coincidence, it may be that ROLAND is needed somewhere in this game
The telephone numbers of Jonah, Elias, Paul, and Hermann are actually ISBN-13 numbers of science fiction books by Isaac Asimov. I was looking to see if they are real phone numbers in a certain nation, then realized they are not, they are ISBN, and searching each number yields an Asimov book
0553803735 = Second Foundation (Jonah's telephone number)
I found the site, here are some first observations