[Dmanj]

If I understand correctly, you have a total of 10 speakers (not counting the subs). Are you trying to run the fronts active and rears passive?

 

[Dmanj]

So you're running coaxial speakers in the rear? what are you going to use for your crossover?

If you're just going to use the amp's crossovers, use channels 3 and 4 for your midrange and misbass front speakers as those channels have a bandpass filter. use channels 1 and 2 for your tweeters and rear speakers.

 

[Dmanj]

I would think you could expand as much as you want. You'd just have to adjust you filters accordingly. You might get a better answer over at http://www.diymobileaudio.com