In Google earth you can right click on the location of the image then save as
Once you are done with your photos, you save them in a folder in MyPlaces. You can give them the same names as the photos.Then right click on the folder name and select "Save Place As..."
Choose the KMZ or KML Format and load it to your software.
If your photos are Geotagged, ...
The vendor is not allowing those images to be called/exported at large scale. I've had the same experience with trying to export Esri basemaps in the layout. You'll have to download the aerial image files (tif, jpeg, sid...etc) and load them in manually into Q, hit a public aerial WMS (in the US many states provide this or USGS provides a 1m service), or ...
In The influence of urban form on spatial costs, the radius used is the radius of the circle that has the same surface area than the analyzed area (accesible area of a service from an urban area with its surrounding area of non-urban land, to simulate monocentric cities).
In any case, using that kind of "authalic circle" seems to me a good option.