To find out if the device is a 7, 8 or 10 inches tablet, you can check this.
One way you can manipulate the device orientation is in every activity, after onCreate(), like this:
// set the orientation of the device
if(isTabletWith10Inches) {
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
} else {
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}