You should always run the ORACLE_HOME/rdbms/admin/utlrp.sql script after running the catproc script. This will recompile all invalid objects. Once this is done you can see how many objects are actually invalidated when you compile your package.
Compiling a package specification will invalidate any package specifications and bodies that reference it. Remember, if you only need to compile the body, then don't compile the specification. Use: