It's going to be a retractable roof. There was a cheesy little casino on the site until they tore it down just last year. That site was never mentioned in all the tv talk. The plans may have been in place for a while.
As far as tourists, yes they will show up. They already do. On top of that, there's the locals like me from all over the country who will be thrilled to see their favorite team come to town. And the A's will end up being my second favorite team like the Raiders and VGK before them.