this should address both of your queries
https://support.symantec.com/en_US/article.HOWTO125953.html
some of the excerpt
Up to ten connections to Symantec Endpoint Protection Manager have been tested and are supported, but you can have any number of connections in your configuration.
When you use replication between Symantec Endpoint Protection Manager instances, the commands that ATP sends can take up to two replication cycles to propagate to all Symantec Endpoint Protection Manager instances in the environment.