Runways are as simple as chairs lined up along the floor or elaborate stages built from risers or custom stages. They can range from 20 feet in a dark night club to over 100'. Some are raised, others are not. Professional runways are usually raised slightly and lit from the top center. A bank of lights point at a 45 degree angle toward the model. Another bank point at the model's back for back light. A third bank is at the end pointed straight at the end of the runway. A well lit show will contain no hot spots. Color temp is tungsten at 3200 degrees kelvin.
Front row is the most exclusive. Some have standing room only for overflow. Floor and background is usually white. A typical show will last 10-15 minutes. The most exclusive model position is the end. The favorite models walk out with the designer. The most exclusive position for designers is the beginning of the week in a fashion week. Not the first show but the first night in the prime spot.
IMG fashion weeks have their own in house staff of photographers who travel the world shooting their shows. Some of the photographers have specific task such as shooting accessories so it is not unusual to see one of them shooting with a 400-500mm lens. Some shoot tethered directly to a server via ethernet link.