Mosaico Pre-header "View in Browser" broke all my tokens in the footer
I can't speak to the first issue, but the second issue (can't "View in Browser" when logged out), I have a solution.

You're looking for the permission labeled CiviMail: view public CiviMail content.  Go to CiviCRM's Administer menu » Users and Permissions » Permissions (Access Control).  Select [Drupal/WordPress/Backdrop/Joomla] Access Control, and check the appropriate box for anonymous users to view public CiviMail content.