Google-maps – way on Google Maps (online version) to make Public transportation the default mode

Such lines are called geodesics and this site offers to draw them in Google Maps. See also this question: Is a straight line on google earth or google maps geodesic?

I was able to import a "my places" map to mapsengine as of late August (maybe they didn't have the feature before).

1. Make a new map.
2. click "import" under untitled layer
3. select "my maps"
4. all your "my places" maps will be listed and you select the map you want to import