Hi Brad, welcome to the forum.
Well, there is a lot of stuff going on here. First, I am a little uncertain as to what your actual goal is for this project and maybe that's because you are a little uncertain too.
If you just want to get it working, all you need is the receiver and a center channel. You choice of the Onkyo 708 is a good one. For the center channel, the goal is to match the sound of the surrounding speakers. In this case, Bose makes a center channel...
http://www.amazon.com/Bose-VCS-10-Center-Channel-component/dp/B00005T3NH
However, when you asked if the Bose ceiling speakers would work and if the AudioSource subwoofer was sufficient, I am detecting that you may wonder if you should rethink and rebuild your system. I say, if you are happy with your system... keep it. But I also say that you can do much more justice to your 56” TV with a better system and you probably owe it to yourself to do so!
Everyone here is going to tell you that ceiling mounted speakers, while great for esthetics, are the least desirable location for good sound. If you and/or your significant other can tolerate the sight of speakers in your room, you can no doubt obtain much better sound that will dramatically impact your TV viewing.
If you want to design a new system, tell us a little more, primarily, the size of your room and the size of your budget. Then you will see recommendations start to flow in.
I don't think anyone will try to talk you out of the Onkyo but we will see...
Nick