Hi, thanks for your questions!
I'm not really going into the specifics of the cost, since we're not using the in game currency from PMDU anyway and I don't want to limit who can join. It can be as much or as little as you want depending on what you need for your stories, just not free. don't get crazy. Most people pay monthly but weekly or nightly can also be arranged.
In either of the situations you describe, Ananna or Clove would handle it, depending on the severity of the situation. The person would be asked firmly but politely to stop the bad behavior and if they continued, they would be ejected from the premises. If they were asked to leave and went quietly they would be offered a refund for whatever rent they had already payed. Ananna and Clove are both strong, and if the person in question put up a fight they would most likley be able to defeat them and kick them out of the place. On the slight chance they were unable to defeat the miscreant, the royal guards or the hunters guild would be called in to help. It's hard to say much more without having a more specific situation.