A little late to ask this about the IDE but ...

[Barry914]

... Where can I find a complete language reference? The online reference is very limited and incomplete. For instance, it seems string functions are supported even if you don't #include the string library. Same with some other standard functions. Where can I find a complete language reference and the libraries included by default and/or supplied with the IDE?

[adafruit_support_mike]

That's probably a question you want to ask in the Arduino forums: http://forum.arduino.cc

As far as I know, the documentation on the website (and included with the IDE) is everything that exists. To go beyond that, you need to dig into the source code.