we use in drupal 7 ubercart 3. here we use this function for update cart page.
This is answer of 2 question.
** hook_form_uc_cart_view_form_alter**. we got a solution .
implementation like..
function modulename_form_uc_cart_view_form_alter(&$form, &$form_state) {
if (count($form['items'])) {
// Add edit column to tapir table.
$form['items']['#columns']['unit'] = array(
'cell' => t('Unit Price'),
'weight' => 2,
);
// Add edit link to all products.
foreach (element_children($form['items']) as $key) {
if (isset($form['items'][$key]['cart_item_id'])) {
$form['items'][$key]['unit'] = array(
'#markup' =>t(uc_currency_format(sprintf ("%.2f", $form['items'][$key]['#entity']->sell_price ))),
);
}
}
}
}