re: Mir's visitors
Mir had 4 things affecting it through time:
Most of the systems, connectors were inside the pressurized modules.
Which made it easier to repair than having spacewalks. Problem was: leaks, moisture, etc...
In weightlessness, things get lost not only because of all the corners but also because any object changing orientation, changes shape and is more difficult to recognize.
Mir had frequent visitors leaving experiments and souvenirs. They could be used and tested long after the visitors were gone.
Mir couldn't easily get rid of things. Any jettisoned object could become a dangerous bullet.