We visited DAQ for the first time this past trip (Jan 19-26) with very, very light WDW crowds. The kids waited for nothing at all except the pirate game and that was still a manageable wait.
I stuck to 9 year old DD like glue because she is so small and gullible. 11 year old DS was given free reign. We had a rendezvous point and I checked there for him every once in a while.
At one point, I noticed I had a missed call from a (407) exchange and calling back, the number was no good. I asked where they would take a lost child and no one seemed to know so I guess they don't have a plan in place like the parks.
I found my son sitting in a chair near the exit in the care of a cast member who had given him a soda. DS claimed to have felt dizzy but I suspect that he had just gotten a little nervous when he couldn't find me.
We returned the next night and I armed them each with a cell phone. I set up a laptop in the restaurant on the fifth floor. They found me when they got hungry. I ordered them food. Then DH called me and invited me to Splistville Lanes for a date night. I left the kids at DQ and had a nice dinner. Picked them up a while later. Everyone was happy.
To answer your question about what it is like. It is five stories of video games, arcade games and interactive games. Other than for food, no money needed unless you want to play one of the three games where you can try to grab a prize. It is loud and very maze like. It is near impossible to find anyone if they are on the move so have cell phones and a strategy (like - meet at XX o'clock).
A CM told us that when the weather is bad DQ gets crowded because no one wants to be outside. He said that when it is crowded, you can end up waiting quite a while to play games.
I don't understand the discount question. Do you mean discounts to get in? We have AP with Water Parks & More so DQ is included. I think it was $45 per person otherwise.