I would love to install/upgrade the "official" templates right away from git, without manual, time consuming search-and-replace procedure. Zabbix should provide a list of available templates on git. It should tell me, if an installed template is out of date and can be updated from git.

The git repository and branch should be configured in the Administration section in git. The default should be https://git.zabbix.com/scm/zbx/zabbix.git (or similar).