Understanding processing options for R43500

Hi All, need some help to understand the processing options of R43500. If I am using processing options and order activity rules as attached, does it mean that:

1) All Purchase Orders which have Next Status as 280 or 400 should be updated to the next status, i.e., 400 and 999 respectively?

If I only wish to update the next status of those POs which have next status as 280, shall I keep " Next Status Code From (optional)" as Blank and "Next Status Code Thru (required)" as 280? In light of our order activity rules, I believe the processing options of R43500 (that we have at the moment) are incorrect. Please advise.