Let me see if I can help you with identifying what each WA product does...
1. Digital File Pro : Provides full server upload/download capabilities of any file type to a developer defined server locations. (meaning that you design the upload page and you as the developer define the directory the files will be saved to) * I suppose you could also identify the upload directory dynamically, but that would probably require a bit of hand coding to accomplish this.
2. CMS : I purchased it, but I haven't used it yet. In general it should provide you with the ability to provide your clients the ability to manage their websites without the need for Dreamweaver and/or coding knowledge.
3. DataAssist : I think if you wanted to create your own CMS, since you own the Super Suite, you could do so using DataAssist and a MySQL table that held all of your website content. You'd just call up the content as dynamic elements on each page. The backend management could be created just as easily and secured using Security Assist.
I hope this helps.