Wow, that's a lot to absorb and study on.

So early on in Naruto, when team 7 is first formed, when Naruto calls Sakura "Sakura-chan" and when Sakura calls Sasuke "Sasuke-kun", are they rudely assuming a familiarity and closeness that may not exist (ie I doubt Sasuke feels as close to Sakura as she does to him) or is it perfectly acceptable to be this informal with each other even at that point in their relationship?