I sort of know the gear – the Yorkville speakers are meant to be really good..
But layout is where I can comment – I would set it out like this (I do a similar event a few times a year where we use 8 speakers in a room like this). This is how we have found makes those rooms sound the best and gets the most even sound accross the floor:

(The tops on the stage are set above the subs.. It’s hard to do with a top-down diagram… 😉
I would run all the speakers from the same mix out on the desk, and adjust the levels actually on the speakers themselves. Once it is set up, you shouldn’t need to touch it (Although remember when sound checking that people absorb quite a lot of the bass – so make sure it is nice and high)..
You may want to see if the company can provide you with something like this – http://www.altoproaudio.com/products/stealth-wireless – it will save running XLR’s down the entire room (like I normally have to.. We normally fly them along the ceiling but that may be impractical in this situation).
bob6397