Hey Robin -- If you didn't make any changes in the settings of your sequence, then yes. By default, email sequences use the default email template in your account. You can change the template for each of your email sequences. Just go to the settings of the sequence and change the email template from there.
Yes, you can also add a link triggered in your email template so that you don't need to add it every time you create another email. You can check out this link to know more how to add a link trigger to email templates: https://help.convertkit.com/en/articles/5281872-how-to-add-a-link-trigger-to-an-email-template-new-email-editor22