CMS system (?) for new website

Hi, I am looking to have a system (CMS?) designed for my website based marketing system. The marketing system consists of PDF’s and podcasts which I want to integrate into my customers website directly from my website/server. They should be able to log into an attractive control panel with icons on my website where they can change what they write in that area at the end of each PDF. They should be able to change the appearance of the directory somewhat, and customize an area at the end of each PDF so they can write whatever they want in that space. They can should be able to customize each article with their own website name and practice name somewhere at the beginning of the PDF and at the end of each PDF so they can write whatever they want in that space. This should also be able to be done in a single box and all changes are made to each PDF in a single click of the mouse. Essentially, this will be a subscription based site, so after they pay their dues, they can access the PDF’s and Podcasts and upload which ever ones they want and it will appear on one of their pages. I DO NOT want their website visitors to be redirected to MY domain name/website. The content/directory must be directed to their website. The system also makes use of a banner that gets uploaded to each homepage,which has a built in opt-in form. An eBooklet gets sent to those who opt-in. I would like to have the eBooklet and its cover changeable as well, but am not sure if that’s possible. I DON"T think it's possible to have the banner on the homepage to be uploaded to someones website via this sytem. But, you can let me know. I am sorry if I could not explain what I wanted well enough. I do not know too much computer lingo/terminology.