The preferences are saved according to the QSettings class of Qt. So you can just use another constructor to make the settings be saved in a .plist file. But you have to replace all of the calls to QSettings to ensure consistency. I know that some of the things implemented, are quite windows specific. Until now I focused not to much on supporting other platforms. Maybe we can improve this introducing some #ifdef statements.
The movement control is done in the keyPress- and keyReleaseEvent method of the GLWidget class. Currently it is hardcoded using a switch statement. But maybe I will change it to be configurable in a future version. What kind of camera control would you propose?
Next to the W,A,S,D control there is already the possibility to hold down the CTRL key (on Mac I think it is called the Command key) and press the mouse button used for navigation while moving the mouse. The mouse button used for navigation can be configured in the settings dialog. Moving along the Z-axis can be realized using a mouse wheel (does the Mac has a mouse wheel?). You can increase the speed by holding the Shift key pressed.
I'm always open for suggestions. If it requires not to much effort I will try to integrate them into a future version. Of course I can not guarantee that everything will work on a mac, since I don't have one