As for Content Elements and its extensibility —we initially considered Content Elements to work with all existing fieldtypes in ExpressionEngine, however since this might not work every time, we’ve decided to use own own fieldtypes, which we refer to as Elements. We opted for our own Elements to:
* speed up the processing of templates (PHP)
* simplify the development process
* make it easier for us to come up with new exciting Elements (eg. generation of ToC, forms etc.)
It’s fairly simple to create a new Element and we’re currently working on a step-by-step guide for developers. Additionally, we’re about to prepare Elements from some of the most popular fieldtypes.
As for the WysiHat fieldtype, we actually support EE’s native rich text editor and you can use the {rich_text} tag to display it. For more information, please refer to the Rich Text documentation.