1) You'll need a regulator with the 255. If you're willing to spend that much, you're better off.
2) Exhaust is a good idea. Good choice.
3) A boost gauge is a must, an egt may not help as much as you'd like.
4) You can get a 14b into 12's, it's been done.
5) Kevin has a fuel worksheet on his site you should check out.