Her feeder bands and her strong area of convection over water is keeping her stronger than one would think for a storm over land. A good part of her remains over water and this trend will continue even more as she moves west. This can be seen on the water vapor loop here.

http://www.goes.noaa.gov/HURRLOOPS/huwvloop.html

I would also think that as she was intensifying and formed over land she would be less hurt by land than a strong storm that hits land after functioning better over water. I don't know if there is any scientific explanation for this but from observation I have seen the mtns of Haiti have less of an affect on such storms.

As for the high pressure ridge, if Fay intensifies as she may be doing would that not help break down the ridge earlier than expected? The models previously kept Fay as a weaker storm at this point and did not account for an intensification.

The waters of the Windward Passage are hot and depending where she hits it she would be over very warm water for some time leading to further intensification.

I would think the models may shift back to the left somewhat if she does intensify.