Lights spots on the ceiling - the best way to get rid of them, it place the land behind the window. I mean to put outside the plane near the window with a dark (the more darker the less light on ceiling) material. You can give a little color and color of light on celing will be the same.

For interiors desired value for ISO - 400 (less do not desirable, will be dark).
f-number - it is desirable stand between 11 and 16, and if you have pictures of a single object, making it the focus (vase in the interior, the phone on the table, etc.) then the value should be small aperture from 2 to 8 .
Shutter speed - it is the value that can be changed to select normal lighting visualization. (! but only when set the value of Film speed (ISO) and the f-number) its limits from 30 to 500, but it is possible and above or below.