We plan on addressing this by supporting the tagging of hosts and groups.You will be able to get a host as "production" or "development" for example, and then assign packages based on the tag; you will also be able to filter results in the web reports based on those tags. Supporting nested groups would require a substantial architectural change, and we believe that tagging offers more flexibility. We plan on offering this in the upcoming v3.4.3 release.
Thanks for the suggestion, this will be improved in the upcoming 3.2 release and included in the next beta release. We've increased the field to 3 lines and it now accepts the enter key.
How would you like to use the variable? E.g., would you like to use it in an email alert such as a subject?
The $GROUP variable already exists (http://www.eventsentry.com/documentation/help/html/configvariablesdetails.htm), but it may not exist in the context you need. Please let us know.