Can a copy of the templates be put in the source tarball in a similar fashion to those in https://www.zabbix.org/wiki/Zabbix_Templates/Official_Templates#Zabbix_2.2.0? This would make it much easier when updating between versions to make sure that no new features/templates are missed.

It would also need a text file highlighting which version new or updated templates were changed?

The file could just have a table with a template name, version introduced, version updated and minimum required version.