Needed Info on Bus Multimedia System!

We am looking to develop a complete multimedia system for a bus. We're open to any suggestions on what this system should have, as well as looking for things we'll need to make this work. If you guys could give us input on components, prices, details, problems anything that will help we don't really know what were getting into yet but its gotta get done!

Things we have want it to be able to do and include...

-four 20in tvs or monitors(what's best?)
-4 cameras(maybe more later), ability to record each seperately and play back simutaniously on screen(want to but video on internet)
-play videos from hard drive(wmv etc) or dvd
-play music
-one backup camera for the driver
-split screens to show some of the camera angles, videos, or dvd

It's a complete system but how can it be done?

What other cool things have you installed in these systems we might want to do?

I appreciate the time you've taken to read this!

Oh ya, we want to be able to play video with full audio on the sound system at times but at other times play video with no sound and music from a seperate sourch on the speakers.