The fastest way to create and configure a Record Producer is to open the table in the Table records and select the Add to Service Catalog Related Link. This will automatically create a Record Producer with the same fields as the table and add it to the Service Catalog. You can then modify the Record Producer as needed. The other options require more steps and manual configuration. Reference: Create a record producer

A Display Business Rule has access to the current, g_scratchpad, and GlideSystem objects, but not the previous object. The previous object is only available to Before Business Rules4. Reference: Business Rule API
https://docs.servicenow.com/bundle/tokyo-application-development/page/script/business-rules/concept/c_BusinessRules.html

"There are two possible ways to respond to events:
- Email Notification
- Script Action" - see this quote in link below:
https://developer.servicenow.com/dev.do#!/learn/learning-plans/tokyo/new_to_servicenow/app_store_learnv2_automatingapps_tokyo_responding_to_events