As for whether they check each person's room key, it depends on what's going on there at the time. My roommate and I stayed there a few years back. On Thursday, only one of us had to show a key, but on Friday and Saturday evenings (when the big parties were happening), both of us had to show our keys to get past security.
I'm glad we stayed there once, but I wouldn't do it again. The security is kind of a pain, and the parties at night can be LOUD. Our room overlooked the courtyard. It was great for celebrity watching, but the music was loud and went on into the wee hours.