Ok, two things I've never seen here at ground zero, eastern eyewall, Katrina: 1) a roof, either gable or hip, lifted off the house 2) a ridge vent ripped off the roof, even those cheap metal chicken coop looking things. Tornado, yes, hurricane, no. It's all about proper installation.
As far as the house having no vents, you just might have a jump on the current trend in Florida toward completely sealed attics with cathedral insulation and light colored roof tiles. It's supposed to be more energy efficient than any vented system if done properly.
Look around the neighborhood and see what kind of vents are common there. If you go with soffit and ridge, use a baffled ridge to block water intrusion. I don't agree with power vents unless there's no way to effectively install a passive system. If "cap and trade" passes, you might end up regretting that energy usage
Just FWIW, my roof, post Katrina, is 30yr laminate shingles, properly installed for high wind area, with full soffit vents at eaves and ShingleVent II ridge vent. When Gustav blew by us last year we got almost 24 hours of strong tropical storm force wind and rain.......zero problems!