What are the largest airports in terms of size, gates, and stands?
According to InsiderMonkey DFW (Dallas/Fort Worth International Airport) is the largest at 4360 hectares.
According to Wikipedia DXB (Dubai International Airport) has the largest terminal in terms of floorspace at 1,713,000 m2 (18,440,000 sq ft) with a volume of approximately 10.0 million m³ (360 million cu ft) 
According to this forum ATL (Hartsfield-Jackson Atlanta International Airport) has 206 gates
Can't find this one