I'm a newbee..Need Help!!! Please..

I need to know the best way to hook up my equipment for premium sound. Here is a list of what I have.
I have a Toshiba satellite laptop running karaoke software. I have it hooked to a Radial Engineering JPC Stereo PC DI box.
Yamaha EMX512sc mixer/amp
2 - Yamaha s115v loudspeakers which I want to use as mains.
2 - Peavey PV12M Monitors.
I just bought a cheaper Technical Pro LZ6200 2 channel amplifier I want to run the mains through. It says the amp puts out 375 watts @ 8ohms to those speakers (which it doesn't seem to be enough).It says it will put out 710 watts @ 4ohms. Can I bridge the 2 mains from this amp? Do I need a better amp? what cables should I use? Any info you pro's could give me would be greatly appreciated...

IF your amp is bridgeable, you might benefit from that, but the hazard then is A) lack of stereo field (no big deal) and B) you might have a problem summing the L/R to mono, depending on the capabilities of your specific gear on that point. A bigger amp might do the trick, but I would definitely get a second opinion on that before u make that leap.
For cables, use actual speaker cables, which are usually noted as such, but otherwise, the feature you're looking for there is gauge 14-12. Heavier cables handle power better.