See, unfortunately while I was sleeping someone decided to delete my ever so helpful post about whats appropriate for a topic. I'll help you out.

RAFO Stuff: For this board, generally it would have to do with a connection of WoT or the WoT Board and posters or maybe the WoT Board functionality.

Theory: This is about theories you might have. When this site was wotmania, it wasn't as important that they were well thought out theories because it had a very good and thorough Theory Post. The board was more of a place to get peoples feel and try to refine your theory so that hopefully it would get reviewed, submitted and great discussion would ensue. Now, at RAFO, its more of a fairly well thought out theory on the books.

Theory really shouldn't be used if what you're after is more of a question. If you're like "Hey, because of this, I think so and so will do/has done/was responsible for such and such" then Character or Miscellaneous would be a good topic. If you have lots to support your question or observation then use the Theory topic.

Sanderson: This is really about Sanderson and his progress on the WoT books. For whatever reason, posts on this board under Sanderson tend to get deleted.

Jordan: Things about RJ, often they tend to be about interviews he's given in the past and things he said.

Survey: Surveys tend to be several questions, but if all you have is a question and you want others thoughts, then this is a good one to use.

The books topics: I generally see and use this for events that happen in a particular book.

Hope this helps.