NHC has a model reference guide available for the models you list at http://www.nhc.noaa.gov/aboutmodels.shtml, but note that some of the information about the dynamical models is a bit out of date.

The Bermuda ridge is a transitory feature; seasonal activity might be slightly related to it as far as it is influenced by ENSO and PDO cycles, but largely it is not the main player in seasonal storm numbers. Since it is a transitory feature, it is largely on a storm-to-storm basis as to whether or not it will be there to allow a storm to track further west or recurve; any statistical correlation is likely pretty small (likely some years with a strong ridge but few storms and/or few landfalls) and we've seen many active years with very few landfalls. We've just gotten lucky -- or are catching up for many years of misses, if you want to look at it that way -- over the past couple-few seasons.