1. The template they fill should be stored in the long text of the Notification in exactly the same way as they are filling in the template. For this, can I use standard text or any other feature?
You can use standard long text to fill the template. Try QQMA0025 PM/SM: Default values when adding a notificationuser exit to get the template details while creating notification.
2. I want to use SAP Personas in front end.
Make more clear about this query. If you want to use Person Responsible & other partners in notification, use Partner Determination Procedure for the notification.
3. A separate notification is allocated for reporting any safety incidents. I dont see this as an issue.
Skipping this as there is no issue.
4. A workflow trigger to certain group of people in the Lotus notes informing on this.
Discuss with ABAP & Workflow consultants to trigger the mail. Its small development.
5. A group wide reporting. I dont see this as an issue.
Skipping this as there is no issue.