Hi @Andrew C
Thanks for the question.
= Custom WYSIWYG toolbar buttons =
Yes, please read this article to create a custom set of buttons (only link)
http://www.advancedcustomfields.com/resources/tutorials/customize-the-wysiwyg-toolbars/
= filter / remove markup =
ACF does not contain a function for this, but I’m sure WP or PHP (please search on google) has a function!
= private posts =
Yes, ACF works with private posts just fine
Thanks
E
