Okay, so this may seem a bit odd, but is there currently any way to upload a file through the zenphoto gallery and then hide it, so that it does not appear as a clickable thumbnail in the album itself, but can still be used as an album thumbnail for the main gallery page? If this isn't possible, I would appreciate workarounds also.

The site is http://mitch.squidlingstudio.com/ (I'm using the andreyphoto theme.)

And I am a total noob at building websites, so I apologize in advance for making you repeat/translate anything in fifth-grade English for me. Thanks so much!

Yes, just upload an image and set it to "not show/unpublished". Then you can still choose it as the album thumb either directly on the left in the images list or in the dropdown selector of the album.