Thanks for all the information. I'm gonna try everything you said plus some trial by error stuff and see what I can make. Expect a very very early alpha build in a few weeks if I do OK learning all of this.
Also working on making an IP.bins (I think that's it) file that has a nice lil segapedia logo on it when the dreamcast boots the disc. Seems to be rather easy to make one of those, so I figure thats a good starting point for me to start learning all of this stuff.