Re: No respect
It would be best if the dojo cho dealt with this. Given that he won't, I don't see why the other senior students shouldn't handle it on their own. As Ashley points out, there is a fairly strong tradition in MA dojos of senior students doing the basics, like enforcing dojo etiquette, which is too trivial to bother the so-important sensei with. (A bit of tongue in cheek there.) So use that mechanism to handle this--your dojo cho is to unworldly to handle this directly, so you guys take the guy aside and tell him his behavior isn't winning him any friends. Since you have no formal power, you may need to use various forms of shunning--e.g. I won't practice with you if you dis the instructor.
Hard situation. Best of luck.