I would have to agree with Xzin. I think micromanaging that many different classes will be overwhelming.

I'm currently 5-boxing a pally, priest, 3 mages. I know the learning curve I went through, and i can't imagine how I'd control/manage the classes you have selected. I'm sure it can be done, but it would come at a cost. I also wanted to have classes that would be multi-boxable in pvp type situations, and for that you want lots-o-dps, aoe, and as little micromanaging as possible. My original plan was for 4 mages and a priest, but for the BC instances, a tank really is needed. When i get to 70 I already have a high lvl caster to throw in the group for pvp to replace the priest.

Why have a warrior and a pally? If the pally will be tanking, he won't be healing. He'll be using his mana to hold agro. In my group, my priest is MORE than sufficient for heals. I'm leveling primarily in instances, and even in the tougher boss fights, my priest rarely uses even half her mana. My personal opinion is its difficult to control more than 1 melee type toon at a time. The mages and priest are awesome ranged classes that you can just park and nuke.

As far as controls, I think the vetra stuff is pretty cool, but I wanted to use a USB keyboard. I'm currently using the Logitech G15 in combination with a modified version of multibox. The G15 gives me those extra keys on the side. I use them for things like setting the focus for each individual mage/priest before a fight. Then each mage has a macro to sheep their focus, that same button on the priest is shackle.

I modified the multibox code to allow switching between screens via hotkey. I then assigned a set of G15 keys for switching between screens. My LCD's are arranged in a 3x2 array, similar to Ellay's. The G15 G-keys are arranged in the same 3x2 array which makes switching fairly easy. I also have another keyboard setup with a KVM switch in case I have troubles different computers, i can just switch over and fix things if multibox isn't running.