In 2004 I rewrote the entire IFI supplied control code (other than the hidden stuff in the library). Should that code work as-is on the 2005 system, or has core components of the IFI supplied library changed?
Yes the code should work. The libraries have changed/optimized to be faster but functionally they are the same. Also new this years is a section of breaker panel and camera code that you would not have had before.