Reference for RPM spec macros (%setup, %buildroot, etc)
Solution 1:
The Fedora Project hosts the best documentation on RPM out there in html format:
http://docs.fedoraproject.org/en-US/Fedora_Draft_Documentation/0.1/html-single/RPM_Guide/index.html
See also:
http://fedoraproject.org/wiki/How_to_create_an_RPM_package
Prior to these resources, my go to guide was Maximum RPM (which you also found):
http://www.rpm.org/
Solution 2:
Some of them are documented in Maximum RPM, Taking the RPM Package Manager to the Limit by Edward C. Bailey.
Section Macros: Helpful Shorthand for Package Builders describes %setup and %patch macros.