hi alex -
auto flash will burst the flash at whatever the high synch speed is, i think it is about 125 / 250/s;
red eye reduction will flash a few times to close the pupil so your subjects don't get red eye;
flash IN is ambient flash, so whatever the meter reads as the view without the flash the shutter will use, AND the flash will burst as a fill-flash;
flash off turns the flash off ...
and landscape from what i remember locks the focus on infinity focus, so if you are shooting out a window,
or are "obstructions" your camera might focus on, they will be avoided, and the landscape will be infocus..
i was suggesting just put it on flash-in ( the lightening bolt ) and using the flash as a fill flash,
regardless of ambient lighting.
have fun!
john