clearly there should be a twin signal that lets twins know when other twins exist.... or they met back when the narukamis were still in hs and a year older, either-or. but yes, they should be twin friends.

also i'm a little disappointed that naegi doesn't mentor hs students, because it'd be fun for her to be a Major Headache...

and yes, it sounds like that's the plan.... kaguya will probably judge the hell out of the two of them. an apartment isn't that flammable.