There are several possibilities as to why the ship can maintain an atmosphere without any visible barriers between the vessel and space. Most of the ones I'm familiar with involve magnetosphere generated forcefields, but the ship is equipped to maintain a variety of physical laws so any one universal theory might prove inaccurate.

Wardens are matched at the middle and end of each month, though may be postponed in the event of a shipwide incident. Criteria for matching are uncertain but all wardens are provided with a file of relevant information pertaining to their inmate. Many inmates ask permission to see their file.