Units

Distances are things like navigation aid range.   It is normal to use nautical miles (NM) for these.

Dimensions refer to things like length and width or runways, size of helipads and so on.   Set this to feet or meters.   Note that the radius of parking spots is set separately.

Parking radius is important when you are setting up an airport for use with AI aircraft (as well as your own user aircraft).   These are generally set in meters and FSX will compare the size of the space with the wingspan of an aircraft as one of the criteria for where the aircraft can park.   FSX has a standard set of parking radii.   You can modify these to suit your needs.

Enter meters or feet for the altitude units.

ADE can handle coordinates in two formats Decimal or Degrees Decimal Minutes (DDM).

Decimal is 30.7654 -123.7876.   DDM is N30 35.888 or W123 17.6567.