Geno, my view is that in the size room that you describe three vertical M22s across the front under the screen would be plenty. Mike's suggestion of doubling them up at all positions would allow for 3dB more output, but at this point you shouldn't assume that it would be necessary. It could still remain a possible option for a later addition.
As to the height of the M22s, there's really no necessity to think of raising them 9". My M22s sounded fine right on the floor when experimenting when I first got them, although I don't use them in that fashion. Tilted back slightly with some type of wedge under the front edge, so that the tweeters point toward the ears, they should do very well.
