A suggestion to solve the "save"... change the icon of the power button to a settings button...

Some of us never actually use the quit button, so finding the option would only be by pure luck (or reading the thread)...
As for saving/restoring, what I normally do, when I just want to give a quick save slot in a short game (like I did in Birdy Birdy), just add a button to the GUI for save and another for restore/load.
And then use:
SaveGameSlot(30, "save game"); // Note 30 is slot number, you can assign whatever number you like, just not 999, as that is the slot used for restart (it's automatic)
RestoreGameSlot(30);
Just remember to check for if file exists, before restoring it, otherwise you might risk someone crashing the game because they hit restore before saving first.

Alternative to the GUI buttons (or you can just use both), you can add those lines to the usual keyboard keys
F5 for save and
F7 for restoring.