Turians "going postal." xD That's true, Saren's the only turian I've ever seen roar like that. I think it's understanable for him to act like that since Shepard could ruin a plan that took... what, 22 years? But now that you mention it, I've realized a lot of my favorite characters who are usually calm villains lose their temper when a plan gets messed up.
His implants seem to be holding his face together, and he had them before Sovereign (on the cover of Revelation), same with the cybernetic eyes. Poor guy. I wonder if he was in some kind of epic battle accident, maybe the second turian we know who tried to stop a rocket with his face. And Saren's body type does look more (I know he would be angry with me for saying this) human than most turians. My theory is that he eats a lot more, probably the equivalent of a biotic before he became a biotic, so it doesn't bother him to go on missions where he can't eat or sleep for days, like in Revelation. It's just a theory though - there really is no explanation for it.
I've seen the inside of Garrus' face on the Xbox too, except I meant to do it. The same thing works to see inside the helmets of dead turians, and to see through the collar of live turians. (All character models appear to end after the neck, then there's nothing else under their clothes.) The Garrus hug banners are awesome, by the way.
@zhongda: Thanks for the link.

About Saren - his appearance is exactly the same before Sovereign based on the Revelation cover, with the exception of the tubes, geth arm, and glowing.