Omeka is clearly designed to display collections, meaning that it would only be effective if you have objects (images, photographs, media, videos, audio, etc.) to present in an organized fashion. I would explain Omeka as the iPhones of websites; in the sense that, iPhones are user-convenient with standard designs, compared to androids that require more prior knowledge to customize. Omeka is not your site if you want complete control over how it looks, though this is restrictive, it is very user-friendly because the layouts and fields are provided for you without having to learn something like HTML.
Searching for items to upload was definitely frustrating when I hit a copyright wall. For example, Triumph of Faith from Bridgeman Images is under a license, and it would have been a good addition to the 19th-21st Century Popular Culture Collection. Like Terras, I agree that it is difficult to reuse/remix digitized content because of copyright or unclear right. The solution she proposes insists on is to declutter the vast amount of images and comprise a good amount of quality content (in resolution and material) under public domain, because it’s all about sharing, right, Mark Sample?
Metadata is extremely essential when it comes to searching. When metadata looks like this (not to call anyone out), it is certainly incomplete and ineffective. Omeka is extra helpful, because it outlines what metadata to fill in, but only is effective when complete. Moreover, the data must be uniform to comply with search engines.
Creating these collections and exhibits for Perpetua and Felicitas, in my perspective, embraces both sides of the practice-theory divide that Fitzpatrick proposes. We are using digital technology (Omeka) to study traditional humanities objects (digitized artwork), and we are asking contemporary humanities questions (in response to Perpetua and Felicitas) to decipher digital objects (digitized artwork). Though we were building collections and exhibits by compiling and classifying information, in essence, we are sharing information to further our understanding of Perpetua and Felicitas, and that is the true spirit of Digital Humanities (according to Sample).