With regards to the icon ranges, when the icon says "1.5k", it is sayin that the distance to that icon is 1500 to 1999 yards.
When the icon reads 600, it means the target is somewhere between 600 and 799 yards.
Icon reads 200 yards, it means the target is between 200 and 399 yards.
When the icon reads 400, it means the target is between 400 and 599 yards.
Etc Etc.
The icon distance simply means "between" what it says and the next higher measurement available to the icon.
By reducing the GV icon range available for aircraft, two things would occur: First, the aircraft would have to actually scout for enemy gv's. No more simply flying though an area and getting scoping out an path 4000 yards (approximately) wide for gv icons. The aircraft would have to actually actively scout for enemy gv's. Second, it would make pilots think twice about just meandering about if it meant getting shot down or at minimum losing parts of their aircraft. It would make pilots think twice about floating around at 200 TAS at low levels. It would lend to the realism side of things, in my opinion. It would force pilots to involve themselves more in not just killing that gv, but also finding it and repescting its firepower be it .30/.50 MG or 20mm/37mm AA fire.