1) One difference between USC and ND's rushing attack is USC has a 2nd and even 3rd "zip" back to go to. As it played out, McKnight got a lot of carries, but it was a fresh #13 that scored the winning TD. But I think ND's and USC's schemes are similar.
I don't know if ND's template for a running game it the "best" for an elite college program. What IS necessary for an NC is building quality depth. This was the difference between Ohio State and both LSU and Florida in OSU's two championship losses. OSU's first team was every bit as talented and fast as UF's and LSU's. However, their 3rd, 4th, and 5th DBs were not on the same level as either of those teams' 3rd, 4th, or 5th receiver; you had OSU guys trying to compensate and getting themselves out of position. Likewise, OSU's 2nd RB and 3rd and 4th receivers were a pretty big drop-off from their first team guys; without contributions from them, OSU's prime offensive players had to carry too much of the load against the wave after wave of bodies both UF and LSU sent out on defense.
2) I haven't seen the Giants play much (I live in Texas); I don't know if I would call what the Steelers do a "power" running game - they just don't string plays out as much as ND did on Saturday to allow the running back to patiently await a seam opening up; instead, they'll just use many of the same blocking techniques as everyone else, but their running backs will run right at you. It's a more physical approach to the same type of running attack that most NFL teams use, and with their personnel, they can wear a defense down and/or require the opposition's front 7 to require more help from the safeties, which opens up passing lanes for their very good corps of receivers.
As for 'Bama, they seem to have more of a traditional "power" running attack. When it's clicking, they will dominate a game. If not, well, remember John Parker Wilson last year trying to pass Alabama to victory in the Sugar Bowl, a good part of the time while running for his life? For 'Bama, not good times. Bad times.