SpeakerCraft or In-Ceiling speakers @ 8 ohms 5-125 watts

[MPDIEHL]

Any amp if driven to clipping will damage the speakers its running.
No numbers or ratings are required to qualify that statement.

Yes you can mix in ceiling/wall speakers with tower or bookshelf speakers to make up a 5.1 or 7.1 system. How well it will work or how good it sounds will depend on the quality of the speakers and how well the receiver can set up the system for you.

There is NO ONE correct way to design a system, it depends on the parts available, the room available and y our personal needs and tastes.

Just have Fun

As far as Onkyo vs. Sony... My last receiver was an Onkyo and its a super preformer, I am now using a Sony ES series receiver and I think its the best I have ever used. If your budget is not up to buying the ES series Line then I would stay with the Onkyo Line as they seem to outpreform the less expensive Sony's