Berardi's book was shit in my opinion. It is basically Precision Nutrition with some half-assed weight cutting stuff thrown in.
Nutrition in any combat sport comes does to getting your bodyfat very low (some might contend that a little fat protects you, but it is by and large a strength to weight ratio so bodyfat generally=bad Any number of articles on T-Nation can help you with that.
Once your bodyfat is in the single digits probably 6-8% would be healthy and let you maintain some level of energy, then you need to start figuring out how you cut weight most effectively. I think that The Art and Science of Making Weight by Cosgrove and Grantham is the best I've seen out there (actually one of the only ones I've seen, but it does a good job).
As far as S&C, Ross Enamait's books rank highly for me, but I think you're better off just training the sport and not worrying about S&C much.