Hi Andy,
Mark referred to the correct link on the WS website. Under the Competition Rules - Boards there are set of Slalom Rules and Fleet Racing Rules (App B).
Please keep in mind that the Slalom rules are ment to the stand-alone Slalom event, and not to Fleet Racing event where one of the course configurations may be the slalom. For this slalom still Appendix B applies.
Regarding the Freestyle/Wave and Speed rules, it is true these rules are not on WS website because these disciplines authorities did not send their rules to the WS (RRC) and therefore these are not published.

Tim, that's a neat way to deal with it.  Might be mathematically the same result.  Not sure.

If you are using mac OmniGraffle is really great for course diagrams. I am attaching the "stencil" with the shapes I usually add to my diagrams. 

Draw Io  https://draw-io.net/ is a free drawing tool that is available for online drawing or as download for offline drawing on Windows, mac, Linux.

Lifeline tension is also covered in the World Sailing Offshore rules.

not that rare situation, may I say.
On shortening course, when RC places the RC boat on the "wrong" side of the mark, as sometime happens, DNF are not that rare.