Jacques, I didn't see your surround placement question until now. Some years ago I experimented a fair amount with a similar placement. I wanted to have, as you suggest, a more diffuse surround sound field than aiming the direct radiating speakers at the listening position would provide. I got the best results by placing the speakers along the sidewalls and aimed toward the back wall. However, rather than the 110 degree position that you suggest, I found that having the front of the enclosure slightly farther forward than 90 degrees gave some direct(although well off-axis)sound that mixed well with the reflected sound.
This may vary with the amount of treble dispersion that the speaker provides, and of course calls for experimentation. Let us know what you find.
