If you would like to be notified for every comment on a graph, tick the check box “Transfer all user comments” by each channel. If left unchecked (default) you will need to use the @slack-account_name-channel_name syntax for comments to be posted to slack. You might use @slack-channel_name if you are only using one account or refering to the first one.
The Slack integration does not provide any metrics at this time.
The Slack integration does not include any event at this time.
The Slack integration does not include any service check at this time.