Zimmermann Telegram: Questions

Why do you think unrestricted submarine warfare was so important to Germany's strategy in World War I? Wouldn't it have been simpler just to not shoot at American ships?
If James Bond, Jason Bourne, or Ethan Hunt had discovered the Zimmermann Telegram, what do you think they would have done about it? How would history be different if real-life was more like spy movies?
What do you think Mexico's reaction would have been if they'd secretly received the Zimmermann Telegram without it being intercepted? Would things have turned out differently? Do you think they would have shown it to the U.S. anyway?
If the American government today intercepted a similar note from a hostile foreign country (an encrypted email perhaps), do you think it would start a war?
Is it possible that any aspect of the Zimmermann Telegram was lost in translation/decoding? What would you ask Arthur Zimmermann if you could discuss with him his actual intentions?