No individual pot rake, the "rake" is $4 every 1/2 hour per player (the good thing is this is regardless of the limits you are playing) referred to as "time up". The game is not necessarily invite only , there are probably 10 or 15 rooms around NYC and Long Island. You can't necessarily just walk in off the street, but once you come with someone that's in, they are very good about remembering faces.
If they don't recognize you, the doorman will walk into the hallway which seperates the door to the room from the door to the outside and speak to you. "Have you been here before? How did you hear about it? Can I see ID?" etc. It's kinda rounders style, cameras on the inside, door locked and need to be buzzed in. The room I go to most often usually has 7 tables on a busy night and around 4 on a regular night...they have an entire tournament set up through the day as well.
The rooms do get busted from time to time, generally the ones who are less tight on security....the one I go to most frequently now seems solid....if they are busted nothing happens to the players except that they cant cash in their chips, which obviously sucks.
Hope this answers some Q's (without blowing up my spot
)