Depending on what you want to spend you could redo the walls and put green board up. There is also buy special paint that is made for humid and damp rooms. You could also put an exhaust fan in.
I don't know if you can get them chipped or not but it probably wouldn't help anyway. If someone finds it they probably won't get it checked for a chip.
As for finding the lost cham it is just a matter of looking and hoping for the best. Searching a night with a flashlight is also a good idea...