Small bottom to mid level home theatre

I would like to set up a "cheaper" home theatre system in a small room that we have. The room measures 8'x8'.
I managed to land myself a gently used Samsung 46" 8000 series for $500.
I plan on running 5.1 using in wall and ceiling for all speakers.
The blu-ray is an Oppo 93 (recently purchased).
I am considering either an Onkyo TX-509 receiver (soon to be released for $400) or a Marantz NR1602. The Onkyo specs looks good and it is only 13" deep (my cabinets will accommodate up to 14.5".
For in wall speakers i am at a loss. I have a bit of an issue with placement. The wall that the speakers and tv will be mounted on are about 20 degrees off parallel from the viewing position. I understand that speaker craft manufacture in-wall speakers..
... that can be aimed. Are there any recommendations at what i should be looking at.
I will also need to place the center channel behind the tv (which will be on a pivot out wall mount to correct for the 20 degree wall offest); is there away that this can work. Can i eliminate the center channel all together?
Is there an in-wall sub you can recommend?

I'm sure others might disagree, but in-wall speakers are not the greatest for the money. I understand their typical markup is 200%. You might look at a very small sub-satellite set up such as the Totem dreamcatcher system or the one from Focal JM Labs. Both sound very nice. Alternatively, I've heard good things about orb audio speakers (sold online only) which are cheap. For an amp nothing will be that great for $400 new.

Plan B. In a room that small, I'd almost be inclined to skip the 5 channel since there are issues with your centre anyway. You will likely enjoy a better quality 2 channel integrated amp and a decent set of speakers (with a small sub). The NAD stuff or a Rega brio would fit the bill. See above for speaker recos.
I second the Gallo recommendation. Get some Reference AVs or the new Stradas and you will have *fantastic* sound. These will sound *much* better than in-wall speakers.

Mate these use to a nice Velodyne 8 inch sub and you will have a fantastic surround sound system for that room...