Bullit has been bit.

I'm a beginner in this boat building malarky so have a couple of questions:

What are the real world advantages of vac bagging the hulls, how much weight do you really save and what strength gain is there?

What about carbon... pro and cons, I guess you save a bunch of weight in using a lighter cloth(much more than vac bagging by my estimate). Whats the down side, I've seen something about poorer collision durability, a little bit more egg shell like, would this be fair? Would you use carbon for the hulls and not vac bag?

I've got a lot of reading to do!