That link is outdated for the Axiom SDK. The current revision can be found in the "Developers" folder that comes with Axe 0.5.1. This will be a lot harder to write in Asm by the way than it would be in pure Axe and I wouldn't attempt something this complicated unless you have a good asm background.
I think your library is the fine the way it is though. If you want to make it more memory efficient, you can split it into sub-libraries. For instance, you can have "LIB7CORE" for the core routines, "LIB7BUT" for all routines pertaining to buttons, and "LIB7WIND" for window routines. That way, you only need to include the ones you are going to use.