Ok, you’ve got lots going on I don’t understand. But I’ll simplify a little
You want a simple popup page that doesn’t have all the rest of the layout (header/footer/etc).
The code you posted is using
That method returns a url pointing to /catalog/product_gallery/id/???/image/???
This new URL is serviced by /magento/app/code/core/Mage/Catalog/controllers/ProductController.php:143
This action gets it’s layout info from the <catalog_product_gallery> element
That element is telling the ‘root’ block to use ‘page/one-column.phtml’ as it’s template file.
This template file is stripped down HTML file that doesn’t display headers or any of that stuff.
So, on to what you want to do
You should be writing your code as a module, it makes it easier to install and maintin, plus it means you can use an license you want on it.
So, say your module is YourCompany_YourModule
You need to have a controller to handle requests, say YourCompany_YourModule_ArtistController
You should have an action to render the biography as a popup, say biographyAction
If you set the frontname for your module as yourmodule then in your custom layout file (/magento/app/design/frontend/default/default/layout/yourmodule.xml)
You should have an entry like this
<block type="yourmodule/artist_biography" name="yourmodule_artist_biography" template="yourmodule/artist/biography.phtml"/>
Then you can get a url to this like so:
That will result in this url
Now, the above example is leaving out all the basic setup you need to do for a module, which you can find it other places. If you need help with that, let me know.