Whenever you select static front page it render the index.php file as a default. If you want to display blog page as full width then please create separate menu for it. Do not select that page as static front page.
We are sorry but the form will not shows from which page the form was submitted. You can use the analytics so can get the details of which page the user has submit the form.
The static front will take index.php file instead the template you select. Please make a separate page and display it to the menu so the blog full width template will take effect.
