I know Iv been posting alot of questions about this and I thank you for the replys. Now im finaly at the home stretch.

I have a Peavey PV14 mixer
Two 15 Inch Peavey PR15's. 400W RMS a piece, 8 ohm.

My questions are:

1. What does it mean to wire my speakers in parallel? Advantages? Disadvantages?

2. Would my impedence change down to 4 ohms?

3. I want to run my PA in stereo. So if the impedence does change down to 4 ohms, would this amp have enough power, 600W a channel? http://pro-audio.musiciansfriend.com/product/Crown-XLS-602D-Power-Amplifier?sku=481586
If not, I could bridge mono the amp and get 600W out of each speaker?

4. What are some rule of thumbs with setting up the PA?
-What equipment stays together?
-What gauge speaker cable is the best?
-That amp I linked to, that uses XLR to XLR BALANCED cables? I'd need two(one per channel?)

5. Anything else I should know?
IM still confused though.

That means id have to take apart my speaker to wire it?
Back of my speaker it says 400W parallel
Can I just buy 2 Crown XLS 200 amps that run 600W bridged mono? Run one speaker for one amp and get stereo sound?