Four subs aren't necessary. Two subs would be just fine. Two 18" subs are going to put out more that four 12" ers IMHO. Another nice thing about the Chase subs having the outboard amp is you don't have to have a plug next to the sub and the amp runs cooler. Plus, if the amp goes bad you can use any amp as opposed to having the amp fixed that sits inside the sub's cabinet.
With all those reflective surfaces constant directivity speakers can help. The Chase home theater speakers would work nicely. The SHO-10 has a 90 X 90 degree horn on its driver so it doesn't mater if you place it vertically or horizontally.
Television: Mitsubishi WD65737 DLP
Processor: Emotiva UMC-200
Amps: Carver AV 806x/Behringer EP4000
Mains: DCM TimeFrame 600 Center: AT 453C
Surrounds: AT 251.1 Sub: Danley DTS-10
Blu Ray: Panasonic DMP-BD655