1) VST answers depend quite a lot on what version of Progress you're running.
However...
ProTop is your friend. The "User IO" screen will show you who the most active users are. To sort it by writes type "b" (to bring up the "sort
B]y: " prompt) and then "w" <enter> to sort by writes. Or view the "Active Transactions" to see who keeps popping up on that list.
2) I don't find "rfutil <db> -C aimage scan verbose" particularly helpful. But if you'd like to try it just use an archived extent and a dummy database rather than a live one.