How do you write a treatment?

I am on my third script, and I have decided to write a treatment for it. I know that a treatment is a summary of the story, but I don't know all the specifics of it. Would you guys be kind enough to fill in the gaps in my knowledge?

I'm wondering:

1) Is a treatment written in the present tense?
2) Should a treatment include the motivations and inner thoughts of the characters, or just action?
3) Do you include character sketches or bios in a treatment?
4) Can anyone point me to an example of a good treatment somewhere on the web?

Thank you very much for your help.