but I recently got the Ranma Memorial Album, and I noticed a couple of
things:

1)  Tofu-sensei's family name is in fact Ono.  Of course, as Kunoichi
pointed out, it's also on the sign outside his office in the early manga.  I
only though to check that out after she pointed it out, however (I'm not
very clever, so...)

2)  The album gives the name of one of Ranma's friends (the one with
the light brown hair) as "Chappatsu", which means "light-brown hair". 
Appropriate enough name, I suppose.  It should also put to rest any
questions one may have about the color of *his* hair, at any rate...  So
far as I could tell, however, none of Ranma's or Akane's other
acquaintances' names are given (aside from the regular "cast", such as
Kuno and Ukyou, of course)