Load existing form and use hook_form_alter to create a custom submit handler?
You can use the 'Available as block ' for webform settings. This option can find at 'form settings'->Advanced settings of your webform. Once it enabled you can render this webform block, instead of your static form as follows.



You can define custom submit handler for the webform, ex: $
form['#submit'][] = 'my_custom_submit_handler';  in form alter,
in that function you can write the necessary code to save and redirect etc;

hope this may help you.