Can mono be passed around a dorm by kissing?

Yes: But also by sneezing, coughing, drinking after someone, etc. Go wash your hands.

Yes: All you need for exposure is contact with the virus.This can be left transiently on surfaces like door handles, doors, etc. That you touch as part of your normal day. Adults randomly touch their face, nose or mouth a few times every hour and this can transfer the germ to a point where it can enter your system. Frequent hand washing helps avoid this mode of exposure.