For both of these you will need to use the Visual Builder.
For the Contact Form:

  1. Open it and click on Add New Field.

  2. Set a title to it and select the Checkboxes type from Field Options. You'll see a checkbox added instantly to your form: 

3. In the Options field write your text with the link to the website's policies: 

Here's a live demo of the above: 

For the Email Optin: 

  1. After you select the Service Provider (I've did this example with MailChimp) go to Email Optin Settings -> Fields and click on Add New Custom Field

   2. Add the custom field which is created in the Service Provider

Further customize that field and make it Required if needed and add links too: 

Here's a live demo of the above: 

Did this answer your question?