Thanks, Paulineward (Sorry if P or Pauline would have done). A/B is great fun - a terrible consumer of time, of course.
I've been curious about the two things, and wondered whether the purpose of "subscribe to question" was to make that person, and not just the originator, aware of any future contributions to the thread. In that way, you would become aware of any 'thank you's.
Regarding the ability to delete, it seems that the site must risk getting clogged up, if it still holds all the questions and answers from way back.
No need to reply. You've been very helpful.. Many thanks.