Hi Callem,
Welcome to Adobe ColdFusion Forum!
Regarding your final question. ColdFusion is a 2 CPU license (1 Quad CPU means 4 cores), which means it would work for 8 core CPU. So, in other words if you have to machine of 4 core each, you can set up one as Dev Server and other as Production Server.
You said:-
I am in the process of setting up a new development server and had hoped to upgrade our secondary prod server to cf10 and take advantage of the development licence use that comes with that. However from my understanding of the EULA it sounds as though we would be breaching it if we left the dev server web accessible outside our own network.
I am confused regarding the above point, can you please elaborate or share the source where you read about it?
Thanks,
Anjaneai