New Post: Visual Editor additional tags

Answering the second question:

<select/> is used to place the new format style as an item on the block, class, or style selectors (based on its settings) in Visual Editor. Likewise, <button/> places the fromat style as a button on the button bar in Visual Editor. These elements are not placeholers or variables.

Please see more on Customizing Visual Editor here: http://docs.composite.net/Console/CustomizingVisualEditor