Q1: I live in a city (approx. 300.000 inhabitants), a University centre of the area.
Q2: I live in a dorm, to enter the dorm you need to have one of the ISIC cards that can open the dorm's door or you must ring for the doorman to open the door (in that case you must identify yourself, say the number of the room you're visiting and leave some identification for the doorman to write down, which you retrieve when you leave the dorm again). I asked the doorman if someone came to visit my room that day, but he said no one did. Only my close family and friends know my room number, and all of them were in our home town at the time. The only other person who knows this is my boyfriend, but he swears he didn't do this, and I believe him. I don't know any other person from my dorm.
Q3: I have a roomate, but she hasn't been to the dorm for almost two months due to holidays and bad weather. I asked her if she thinks that the envelope was for her, but she said she expected no mail and that she doesn't think it could be for her. Our room is at the end of the centre part of the building, next to it on the right is another hall (at the 90° angle), so no doors directly next to ours; I knocked on the door directly to our left to ask if they think the envelope was for them, but no one was there. Across the hall are readings rooms, no one lives there.
Q4: Yes, it was in pen, in cursive, the handwriting doesn't seem familiar to me (or to any of my friends that I showed it to).
Q5: I have never heard of the quote before, the only Einstein quote I know is on one of the pictures that switch on my desktop background: "Logic will get you from A to Z, imagination will get you everywhere." I don't know if the picture/quote thing means anything, but even if it does, and I should be doing something to prevent some sort of a problem, I don't know what that could be... Or what problem should I prevent.
And yeah, I managed to trace the type of the camera that names the file DSCN, it's a Nikon coolpix camera...