Form and template cleanup - better invocation of $form->add('checkbox'...

I am getting the following warning:

User deprecated function: Attributes passed to CRM_Core_Form::add() are not an array. in CRM_Core_Error::deprecatedWarning() (line 1053 of /var/www/html/sites/all/modules/civicrm/CRM/Core/Error.php).

PR coming up to fix this...