I too built my own MVC and I also ran into the same problem.
The way I solved it was using the extract function. For example:
extract( $this->_tags, EXTR_PREFIX_SAME, "wddx" );
The way I work is every piece of data I want to use in a view, I add to the tags array, then just before the view is rendered the above snippit will run.
Also it might be worth having a main controller that all your other controllers extend. The main controller would take care of setting scripts, styles and data for the view.
If you need any inspiration I recommend taking a look at larvel. In my opinion it is one of the best frameworks around.
I'd be happy to answer any other questions your might have
Edit: Just had a closer look at your code, it doesn't seem like to you are getting the data from the model. It looks like to are just setting it to a property in the model but not using it in the controller, so your view would not have access to it.