Also see: processing-2.0b7\modes\java\keywords.txt

the word "length" doesn't seem to be there... at least not for array... 

length is there, with the other String methods.
This file isn't to be understood and even less modified: it is used internally by the PDE to know which words to highlight, and how.
In recent beta versions of Processing, I saw some glitches in the syntax highlighting, particularly when going from bottom to up, and stuff like that (all the code seen as comment or similar).
Hopefully, there are temporary glitches when going on the path of improving it.

Note that highlighting is cosmetic, just for display. So if switch isn't highlighted, it doesn't prevent it from working!

If there are syntax highlighting errors, please file a bug so that Casey knows about it. We have a tiny number of people working on this and can't catch everything ourselves.