Kahhori isn't in Marvel Comics. Marvel has many well-known and established characters, but this name doesn't ring a bell among them. It could potentially be a new or lesser-known creation outside of the Marvel realm.
Luigi comics are funny for several reasons. The art style might be exaggerated and visually amusing. The storylines could be full of slapstick comedy and witty one-liners. Plus, Luigi's own quirks and misadventures make them a laugh riot.
The little hair curls in front for guys in cartoons might be there to convey a sense of playfulness or to indicate a particular character trait. It could also be a trend in the style of that particular cartoon.
Well, it could showcase the initial awkwardness of getting to know each other, or maybe highlight the differences in personalities and how they affect the living situation. Maybe there are shared hobbies or conflicts that drive the story.