Last Action Completed/ Next Action

I would start with trying to pull the necessary actions from RE using a constituent export:

• Last Action fields, using the Action Status criteria to only pull the last completed action
• First Action fields, using the Action Status criteria to only pull the first/next action

Otherwise you'll need to pull all actions and apply criteria in the report itself.  If you have a lot of actions the first option might be the best, although it will also depend on how you define "completed" actions and if you can use the Action Status field to determine completed or not.