I leave most of that to the John and the others in the team, but as far as the template options are concerned, here is the story:
There is currently no support for multiple templates.
This is in the pipeline though, and that will come later in the year.
In any case, this doesn't prevent you from doing anything you want to do, it just has to be done in the usual Joomla way... overrides.
In order to copy and modify the existing template, copy the files to your Joomla template folder and modify them there. No extension in the Joomla world does overrides with as much power as Ninjaboard does... whether it's php, css, js, or image files, they can all be overrided in the proper Joomla manner. Read about how to do that here: