I suggest you enable support for FreeText fields by Queue. So OTRS administrators can create FreeText fields by Queue.
As a service manager I would like to be notified during several steps of an escalation. E.g. when having a queue based escalation, I want to be notified after 30% and 50% and 90% of reaching the escalation time. So in conclusion it would be great if you could change the "Notify by" field type to multiselect except of dropdown.