I think the region will consist of the eight major islands and every island is gonna have it's own gym bzw. some of the islands are probably a bit bigger than the one in the trailer and have two gyms.
This is GF so unfortunately no.. they afraid the kids will complain "too much land" and will drop it...
I love the simplistic vibe to the region, characters and Pokemon. The graphics are breathtaking and the region looks very tropical and wild; Masuda wasn't kidding when he said they were going back to basics. Which was a wise choice.