Hi,
I want to add a second gallery.php that displays the photos in a different way. Do you have any suggestions on how to do this?

I am thinking of the following setup regarding my sites structure:
Homepage: 10 of the last uploaded images as fullscreen slider
Overview: 100 of the last uploaded images as thumbnails in a grid
Gallery: Usual gallery with different albums and categories
Blog: Zenpage

So I need to create duplicates of gallery.php and integrate one as a frontpage that shows upon entering the site ("Homepage"). Another copy will provide the "Overview" and the third menu item will be the standard gallery.

My question is how to link to these "custom" pages while maintaining the zenpage function? Suggestions?

You will have to use the custom page feature as explained on the theming tutorial. You will probably have to do some work manually. You could use index.php directly as the homepage (see default theme), gallery.php for the gallery and a overview.php page. The blog is always on /news.

To generate links use the menu manager plugin. The Zenpage theme switchest to use that if you enable it. You will need to create a menu set to fit your needs afterwards.

Thanks. That helps me a lot!