in reply to Message Inbox nit
Submitting the form again won't send a message again unless you have reselected a destination for the message. The page always loads with "Don't send" selected. The radio buttons for selecting who to reply to have nothing to do with move/delete functionality so perhaps you are confusing these radio buttons with the checkboxes used for selecting which message to move/delete?
My main complaint is that the "move to" drop-down should default to "Archive" (unless only showing archived messages, in which case it should default to the inbox), and that the "Don't reply" isn't in line with the other radio buttons.