there is a mod around called TwoBox Toolkit it makes things like sharing quests a breeze, because your alt's auto accept them.
And setting up those keys along 1 to = is fine and u wont have any drama at all. I find using the numpad is great for macro keys but you have a fancy keyboard so you probably wont find yourself short on available keys to use.
As for how you should split your screen im not sure, ive always liked 1 client to 1 screen, but seeing your using a massive screen how about going something like main on the left hand side and splitting your 2 alts on the right hand side, one going top and one going bottom. Maximizer in keyclone will help you set that up.