How can I know the ZendFramework version that Koala is based/depend on?
You find the version in the file include_path_version located in the root directory. For the current version 3.7 see https://github.com/koala-framework/koala-framework/blob/3.7/include_path_version.
Another way to be sure is to install the framework and open the file Zend/Version.php and have a look at the constant VERSION.