Not to appear unhelpful, but you really do need to read ALOT of what's already posted here. All of your questions regarding software, setup, key broadcasting, etc, are already answered.

You should be able to comfortably run 5 instances of WoW on the hardware you have. Your weak point is the half gig of memory rather than anything else.

But, really, have a trawl through the posts here. Use the search facility if needed. As a further hint, software that will help you achieve your aim might include "multiplicty", "keyclone", "multibox" and "synergy", all of which are discussed to death and back in various threads.

Have fun!