Re: Roommates doing weird things
@DMDragonCT Thanks for the info on that mod :D I temporarily put it in my game & confirmed that everything I was seeing is by design and definitely not a bug. Thank you @crinrict for helping me figure this out. Any further details than that would be very heavy with spoilers. I will add a few details below for anyone interested, while trying to keep the spoilers at a minimum.
For anyone who would prefer to keep things about their roommates a little bit more of a mystery, please do not read any further than this.
***SPOILERS BELOW***
It turns out that roommates do have special hidden traits that were added to the game with the Discover University EP. These "roommate" traits are completely different and separate from their permanent traits and appear to be randomly assigned to the NPC at the time you ask & they accept to be your roommate. The list of possible traits is quite long with each trait accounting for specific behaviors and actions that the roommates will take.
For example, the roommate I mentioned that sits on the toilet for 30+ minutes has a trait called "Bathroom Hog". It's actually quite funny & very realistic now that I see the intent of the developers! I mean, who hasn't had a roommate or family member who hogged up a bathroom? My sister used to take forever in there! xD All of the odd behaviors I mentioned in post #1 can be attributed to various roommate traits.
One last thing that I have noticed is that these traits are removed from that NPC as soon as they are no longer your roommate. If you ask the same NPC to be your roommate a second time, they will receive new random roommate traits. I haven't yet found a cheat or mod that will let me add/delete/change roommate traits but I will keep looking.