Faculty criticizing students in front of other students
The answer to your two question are:  YES! - Faculty members should have the same code of conduct towards graduate students? Why should an undergrad be treated with any less (or more) respect than a grad student.

And...

NO! It is not appropriate for a professor to discuss negative intellectual or personal qualities of their graduate students in front of other graduate students? 

This all falls under the realm of basic human decency.