nkeynes, is the NullDC source code actually of any use to you? I know NullDC was and still is a Windows only DC emulator - but there must be something useful there? Or is it all code that can't be helpful for lxdream in any way, shape or form because it relies on things in the underlying Windows architecture?
I don't know much about anything so sorry if this is a retarded question, but I'd appreciate an answer.
Possibly not as much as you might think. The code is structured differently enough that one can't generally just copy stuff across, and the hardware is actually fairly well understood at this point anyway. What still needs to be done in lxdream is mostly just optimization and filling in a few remaining holes. Oh and rewriting the audio system, but the MAME has had that part available for quite some time as well.