Writing for animation...

I would treat it just like a regular screenplay (live action) in style and format. You can download scripts online (google search for drew's scriptorama) for example and may want to pick up the Screenwriter's Bible by Dave Trottier for more advice on format, structure, style and such.

I would think you should write it in regular spec style, as well...though some screenplay books I've read say it's okay to add camera directions if you're writing animation. Eh. Beats me.

I would use camera directions in later drafts when the spec itself has been reviewed on it's own merits without the glitz.

Joe is right there on the camera directions - usually if they are in there from a 1st time writer, the producers are going to wonder how you see your role (you are infringing on the director by putting in such things as camera directions).
You can still include movement and such like, just don't dictate what the camera has to show. Its the same for animation I believe. (dinomonster.com should know)
Trottier's book is tremendous and well worth a look, Lost Pin.
Good luck!

Nique