Bi-amping Stereo Speakers from an AV-Amp, 7.1 into 5.1

Hey all,

I've posted on here asking about where to start with an AV amp that's also good for stereo (radio, CD and iPhone) but I don't know anything about bi-wiring from such an amp.

If I simply have 2 sets of speaker cables running from the amp to the main speakers, how will that work for surround and stereo use? I imagine the main speakers will sound better for stereo and surround use, but how do I set it up? Do you set the amp up telling that the front main speakers are bi-amped, or does it work it out on it's own?
And, do you effectively put half the amount of power to them than the other speakers (centre and rears)? i.e. If you have 100w/c, with 100w going to the centre, and 2x100w going to each front speaker, they'd be at completely different volumes if given the same power?

I could just run the front speakers with single speaker cable and use the jumper cables, but I want the best out of what I have.

Tim