Hard to see why it shouldn't be. They could create a Beer Garden type atmosphere down the first base line. As long as there is some sort of shade structure...
There was beer sold at weekend games this year, along with Woodstock's Pizza. I had to double- check just now to make sure I didn't time warp back to January because I thought this wasn't news anymore..haha.
Not sure. I didn't see it every game I attended (only went to 5 total + 1 in Sac). On the days I did see it there didn't seem to be a huge demand, but I think people were caught by surprise.