Though it's not Hobie 16 specific, by far the best book I've found that's still currently available for novice catamaran sailors is the revised edition of Phil Berman's classic
Catamaran Sailing from Start to Finish (not to be confused with the more advanced
Catamaran Racing from Start to Finish 
)
After having looked through many different catamaran instructional books, as well as the UCLA Marine Aquatic Center's cat manual, I and several of the other UCLA sailing instructors advise students to pick up the Berman book as it covers pretty much everything you might want to know.
Also, check out Hobie U's website for a large, but comprehensive download about Hobies and sort through it for material pertaining to the 16. Both the Berman book and Hobie U materials are on my coffee table right now (and they don't impress anybody but me, and maybe my wife

)