Yes it is, and you would be a fool not to carry. Mostly a safe environment however there is always some report of BS trouble makers. In the past there has been roving groups of teens that attack random folks. But like I said for the most part very safe, just with a large crowd you never know. Don't leave home without it.....
There is no mention of it in the FAQ for thunder so good question. I found on other forums that NO you can not but they were old post from 2009. People were challenging it so it very well may have been over turned. Google it. I'm not gonna post other forum pages on the forum. Here is the link for the thunder FAQ.
According to the website there are some "acts" booked. I have no idea if the military will make and appearance or not.
I was there last year on a balcony at the Galt House. Present was a former Air Force surgeon who was giving us the run down of all the aircraft. It was pretty awesome. The Harrier jet that hovered over the river was right at the level of our balcony. A little kid there asked "is he going to shoot us!".