Okay so I'm just a simple PHP dev, would someone be so kind as to point me in the right direction to start learning what I'm going to need to write for the in game CPU, so I can try and get a jump on things?
Never think of yourself as a simple X dev. While you may not have the same experience or background as someone else, that alone doesn't take away from you being a developer (keeping in mind I don't know your proficiency or length of time as a developer).
That being said, since it's going to be a virtual CPU with what seems to be a system based on 6502 opcodes (or similar), we can assume that this means there will also be an opportunity for abstraction/compilation to that system. Basically, there would most likely be cross compilers available in a matter of time that could aide in the development so you don't have to learn ASM or anything that low level. If you want to learn for the sake of learning, and with a great chance of being able to implement that new knowledge in to this game, then learn C - it will teach you a lot more about lower level development and would be a great candidate for a cross-compiler when one were to come out (ex: http://www.cc65.org/)
(0x10c.stackexchange one day?)