Just got pack, and had the UPH passes that include DQ.
There are no additional charges for any of games inside DQ. The food is expensive, but no need to eat there.
My DS (10), and DD (8 1/2), and loved DQ, we went at least three times.
DQ opens at 11:30 am. Locals can buy annual passes to DQ for about $55, and if you're going during value season when all Parks except Epcot close early, DQ can get crowded in the late afternoon and evenings.
We stayed on-site (Pop Century) and had a car. So what worked really well for my family was Early Entry in the morning, followed by DQ in the early afternoon. Rest at the hotel with a nap, then back out again for evening activities (fireworks, Epcot (open to 9 pm), Pleasure Island). No crowds at all at DQ in the early afternoon (this was during week of Jan 5-9).