When I was in high school we used to have many contests... techers vs students, which class is the loudest, best prop/cheer for each class, some prices to win... it was lots of fun!
Intel core i7 would be the best one... but also most expensive one too...
I think you should be fine with the i5-520M (2.40 GHz up to 2.93GHz with turbo boost).
Depends what car you put it in (assume it's either 240sx or Mazda). I'm not a big fan or rotary engines, so I would go with the SR20det.
If you're going with the 240sx, I would also check out the RB25DET or RB26DETT (with the RB25 tranny).
It's hard to tell, but if you think it went well then let's hope it's a good thing.
If they have few more people to interview, most likley they will not discuss any salary with anyone until they pick a candidate. Besides, it's good that you did not ask about the salary... sometimes employeers...