What is Rear View used for?
Rear View is handy as a job position history — new people can see what was approved in the past by their job position. Rear View also lets you see what action someone in your approval group performed.
What is the difference between the "Performed Actions" list and "Rear View"?
Things you have actually done vs. things you had an opportunity to do (whether or not you did them).
In my Rear View, a slip showed as "Open" but it did not appear in my Pending Actions? Why not?
The routing action you could have performed was completed by someone else. But there are other actions on the form yet to be completed. Thus the slip is still open.