Sound genjutsu works through the hearing senses of the victim, as far as I know, the sharingan, a dojutsu that specialize in vision genjutsu, wasn't proven to be able to break it.
And they didn't see through it, they knew that they were in genjutsu, any shinobi would know that.
The white rage technique doesn't last long, but during that time the victim is helpless, and again you say Sasuke only needs to stream his chidori, are you implying that Sasuke can do that when he's in a state like this:
You must be registered for see links
??
And what you're talking about is the first time Sasuke used Susanoo, now he can use it anytime he wishes with no problem, and yes it would take less effort to maintain Susanoo than dong chidori nagashi, since he doesn't need to raise his hands to channel the lightning chakra. All he needs to maintain Susanoo is to just activate his EMS, no movement or hand seals are even needed.
Why didn't Kabuto use it again. That answer belongs to Kishi, I think it would be lame to repeat the same move over and over when he's got other OP moves up his sleeve.
Sasuke can turn the entire cave into black flames? Kabuto can change the entire terrain with
You must be registered for see links
and
You must be registered for see links
.
Once again, Kabuto is the obvious victor here. U_U