This is what I have seen after a review of the NCM interface; when I manage the Nodes there is no grouping option to group based on NPM Groups that I have created. I can group by type, or Custom Properties I have created. Since I manage by Region and Buildings I can choose a whole part of the campus, or specific buildings to narrow down. But these are NPM Custom properties.
The Advanced Alert Menu, offers no NCM Options. But you can alert of the groups as stated a few times above. What condition are you looking to trigger your alert?
You may want to build out a few custom properties to bring your nodes together for the grouping or alerts you want.
Also, SQL Alerts are awesome. A good way to build on your simple alerts it to set them up with the conditions, then change the alert to a sql and it will provide the code the you can further customize and create more advanced alerts.
*as far as the Alerts go, use ONLY the Advanced, as the Basic alerts are something left over from old versions and is too simple for today's alerting purposes*