Dual-boxing on 1 screen

As of now im going to play 2 characters on the 1 screen in 6 months-a year when a can afford ill buy 3 more comps and fix my 2nd one(Sigh being 16 and only having a part-time job :( ) I have AHK im going to buy keyclone today most probaly but for example if there on follow i have to wait for the following character to stop to cast so can i link the keyboards complety so when i hold down "w" it holds it down on the 2nd screen also is there a way to make the mouse work on both wow clients

Not really. Using 1 PC Sort of makes it fairly difficult for mouse control. What I'd recommend is horizontally spanning both of your characters across the monitor, this way you can see what is going on with both AND can move your mouse to click on things relatively quickly.

Good luck.