How to prefill address field forms?
Add something like this to your hook_form_alter() or hook_form_FORM_ID_alter():

  $form['field_address'][LANGUAGE_NONE][0]['#address']['country'] = 'US';
  $form['field_address'][LANGUAGE_NONE][0]['#address']['locality'] = 'Livermore';
  $form['field_address'][LANGUAGE_NONE][0]['#address']['administrative_area'] = 'CA';
  $form['field_address'][LANGUAGE_NONE][0]['#address']['postal_code'] = '94551';