Because this is a Drupal system it is also possible to add the specific html tags to the “filtered html” text format. Or to just make “full html” to the default text format that should be used by the users, which I wouldn’t recommend.
And for the spoiler stuff: Did you add that functionality by using http://ckeditor.com/addon/spoiler ?
As far as I know it is very easy to add additional custom buttons to the toolbar.